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Mechanical properties of A356 and ZA27 metallic syntactic foams at cryogenic temperature
Journal of Alloys and Compounds 813 (2020) 152181
Contents lists available at ScienceDirect
Journal of Alloys and Compounds journal homepage: http://www.elsevier.com/locate/jalcom
Mechanical properties of A356 and ZA27 metallic syntactic foams at cryogenic temperature T. Fiedler a, *, K. Al-Sahlani a, e, P.A. Linul b, c, E. Linul c, d a
The University of Newcastle, School of Engineering, NSW, 2287, Callaghan, Australia Politehnica University of Timisoara, Faculty of Industrial Chemistry and Environmental Engineering, 6 Vasile Parvan Avenue, 300 223, Timisoara, Romania c National Institute of Research for Electrochemistry and Condensed Matter, Aurel Paunescu Podeanu Street 144, 300 569, Timisoara, Romania d Politehnica University of Timisoara, Faculty of Mechanical Engineering, 1 Mihai Viteazu Avenue, 300 222, Timisoara, Romania e The University of Thi-Qar, Engineering Collage, Department of Mechanical Engineering, Nasiriya, Iraq b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 11 June 2019 Received in revised form 3 September 2019 Accepted 5 September 2019 Available online 5 September 2019
This work presents compressions tests of metallic foams at cryogenic temperature. The investigated syntactic foams were manufactured by combining a packed bed of expanded glass particles with either an aluminium or a zinc matrix using infiltration casting. Uni-axial compressions tests were performed after submerging samples in a bath of liquid nitrogen with an equilibrium temperature of 196 C. Both the solid matrix material and syntactic foam samples were tested. For comparison, room temperature reference data from the literature was obtained. In addition, the effect of thermal treatment on the mechanical behaviour of both alloys and their foams at cryogenic temperature was addressed. The results indicate significant embrittlement at cryogenic temperature; however, aluminium and its foams are less susceptible to this effect. © 2019 Elsevier B.V. All rights reserved.
Keywords: Metallic syntactic foam Cryogenic temperature Compressive testing Mechanical properties Deformation mechanisms
1. Introduction Metallic foams are in essence a metallic matrix containing gaseous pores [1]. As a direct result, the relatively high density of the metallic matrices can be reduced. However, their main benefit is the creation of novel properties due to the internal porosity. First, the pores can collapse under load allowing a foam to compress without significant transversal deformation. Paired with a nearconstant deformation resistance, this makes metallic foams attractive for impact protection [2e4]. For interconnected pores, the large internal surface are of the electrically and thermally conductive matrix suggests functional applications such as electrodes, catalysts, heat exchangers, or the absorption of electromagnetic waves [5e8]. Whilst sharing some of these properties with polymer foams [9], metallic foams further exhibit superior resistance to chemically and thermally aggressive environments [10,11]. The inclusion of porous particles has also been successfully pursued for building materials in order to improve environmental sustainability and the mechanical properties of mature concrete
* Corresponding author. E-mail address: thomas.fi[email protected] (T. Fiedler). https://doi.org/10.1016/j.jallcom.2019.152181 0925-8388/© 2019 Elsevier B.V. All rights reserved.
[12,13]. The current study focuses on the use of metallic foams at cryogenic temperatures. Metallic foams may be attractive for cryogenic applications that benefit from large internal surface areas, structural damping, impact protection, and a decreased thermal conductivity. For example, Dixit and Ghosh investigated the usage of aluminium and copper open-cell metal foams for passive cryogenic radiators [14]. They suggested utilization of the large volumetric foam surface area for improved heat rejection to control temperature in space vehicles. To date, little research has been conducted to understand the mechanical behaviour of metallic foams at cryogenic temperatures. Linul et al. [15] investigated the compressive properties of closed cell AlSi10 foam with diamond shaped stainless steel reinforcements. They found superior strength and energy absorption at cryogenic temperature compared to room and elevated (250 C) temperature. These authors further observed a transition of the deformation behaviour of the AlSi10 aluminium matrix from brittle (cryogenic) to ductile at elevated temperature. The current study considers two different matrix metals, i.e. the ZA27 zinc alloy and the A356 aluminium alloy. Metallic syntactic foams (MSF) were manufactured by combining either alloy with porous (~87% particle porosity) glass particles. Half of the produced
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samples were then subjected to thermal treatment to improve the matrix properties whereas the remaining samples were tested in the as-cast condition. Compression testing was performed at cryogenic temperature (~196 C) by submerging the samples in a liquid nitrogen bath. According to author's knowledge, up to now, there are no experimental results with respect to the compressive mechanical behaviour of metallic syntactic foams at cryogenic temperature. Analysis of the obtained test data allows the quantification of mechanical performance at cryogenic conditions. Further comparison with room temperature test data reveals embrittlement of both alloys and their metallic syntactic foams. 2. Methodology
Fig. 1. Samples: ZA27 foam (left), solid ZA27 (centre), A356 foam (right).
2.1. Sample manufacturing All samples were produced using a well-established infiltration casting process [16]. In brief, a packed expanded glass particle bed was confined inside a cylindrical mould. The expanded glass particles were obtained from Dennert Poraver GmbH, Germany and exhibit a diameter rage of 2e2.8 mm with a particle density of 0.33 g/cm3 [17]. The mould was then inserted into a cylindrical crucible with an inner diameter that slightly exceeds the outer mould diameter permitting relative motion of these parts. The crucible contained either ZA27 zinc alloy or A356 aluminium alloy (both obtained from Hayes Metals Pty Ltd, Riverstone NSW, Australia). The nominal chemical compositions of these alloys are presented in Table 1 below. The assembly was then inserted into a furnace and heated to either 530 C (ZA27) or 720 C (A356). Once the metal was completely melted, the assembly was removed from the furnace. A 9.81 N force was applied to push the mould into the crucible and force the melt to infiltrate the voids between the packed particles. Excess melt escaped through a small hole centred in the top of the mould and was subsequently machined to obtain the solid samples. After cooling at atmospheric conditions, samples were manually removed from the crucible. Half of the samples were subjected to thermal treatment to enhance the metallic matrix properties. To this end, the aluminium alloy was solution heattreated at 540 C for 16 h prior to quenching in icy water. Next, these samples were aged for 10 h at 160 C. The ZA27 alloy was solution heat-treated at 365 C for 1 h before quenching. Aging occurred at 140 C for 24 h. All samples were then machined into a cylindrical shape (see Fig. 1) with decreased dimensions for the solid samples due to the 100 kN load cell limit capacity of the testing machine. For simplicity, the following naming convention is adopted in this text: matrix (Al or Zn)/thermal treatment (e or T)/testing temperature (RT or CT), where RT stands for room temperature and CT for cryogenic temperature. As an example Al/-/CT MSF corresponds to an as-cast aluminium foam tested at cryogenic temperature.
min was used in all tests and the main mechanical properties of the investigated samples have been determined according to the international standard ISO13314 [18]. The compressive load and the crosshead displacement were recorded during the tests by using a software embedded in the test machine. Prior to experimental tests and in order to achieve a homogenous temperature distribution in the mass of the samples, both the solid matrix material and metallic syntactic foam samples were submerged and precooled for 20 min at 196 C in a bath of liquid nitrogen. Further, to prevent any temperature reduction after precooling, the samples were held and tested inside the cryogenic device. In order to evaluate the deformation mechanism, a sample from each category was tested “interrupted” at different deformation stages (i.e. 0, 5, 10, 20, 30, 40 and 50% strain). Initially the sample followed the same procedure as outlined above, with the exception that after reaching each deformation stage, the compression test was stopped (first stage at 5% strain), the sample removed from the cryogenic device and photographed. Then, the sample was again submerged and precooled at 196 C for 20 min, and tested to the next stage (10% strain), removed from the device and photographed. This procedure was followed up to a 50% strain, following a 10% strain increment. 2.3. Data evaluation The measured force-displacement data was converted into engineering stress s and strain ε based on the initial sample geometries (see Table 2). All foam data was further processed following ISO13314 to determine effective material properties. Where present the first maximum compressive strength was chosen to quantify the initial material strength, for all remaining samples the 1% offset yield stress was used instead. The plateau stress was calculated as the arithmetic mean between 20% and 40% macroscopic strain. Finally, the energy absorption efficiency was determined to investigate the variation of compressive deformation resistance using
ð 0:5
2.2. Testing Quasi-static uniaxial compression tests were performed on an A009 (LBG TC100) electromechanical computerized universal testing machine, equipped with a maximum compressive load cell capacity of 100 kN. A constant nominal cross-head speed of 10 mm/
Table 1 Chemical alloy compositions (material data sheets). Alloy
Chemical composition
A356 ZA27
7.2 wt% Si, 0.4 wt% Mg, 0.1 wt% Fe, 0.12 wt% Ti, balance Al 27.0 wt% Al, 2.0 wt% Cu, balance Zn
We ¼
0
sdε
0:5,smax
;
where smax is the maximum stress observed up to a strain of ε ¼ 0:5. 3. Results 3.1. Physical properties Table 2 shows the physical properties of all samples manufactured for this study. It should be highlighted that physical data is
T. Fiedler et al. / Journal of Alloys and Compounds 813 (2020) 152181
3
Table 2 Physical properties.
Aluminium A356
As-cast
Designation
Diameter [mm]
Height [mm]
Volume [cm3]
Mass [g]
Density [g/cm3]
Al/-/CT (solid)
17.52 17.45 28.36 28.33 28.34 28.32 17.60 28.34 28.35 28.36 28.29 17.58 17.60 28.35 28.42 28.43 28.40 17.60 17.62 28.40 28.43 28.43 28.40
26.31 26.24 42.34 42.30 42.26 42.40 26.36 42.40 42.32 42.45 42.34 26.37 26.31 42.61 42.42 42.40 42.41 26.33 26.36 42.40 42.40 42.44 42.30
6.34 6.27 26.73 26.65 26.64 26.69 6.41 26.73 26.70 26.80 26.60 6.40 6.40 26.88 26.90 26.90 26.85 6.40 6.42 26.85 26.90 26.93 26.78
16.83 16.44 31.31 30.52 30.37 31.71 16.68 31.44 30.52 31.11 30.19 29.73 30.28 51.06 50.13 49.92 49.54 29.30 30.12 50.98 49.93 49.73 48.75
2.66 2.62 1.17 1.15 1.14 1.19 2.60 1.18 1.14 1.16 1.14 4.65 4.73 1.90 1.86 1.86 1.85 4.65 4.69 1.90 1.86 1.85 1.82
Al/-/CT MSF
Zinc ZA27
Heat-treated
Al/T/CT (solid) Al/T/CT MSF
As-cast
Zn/-/CT (solid) Zn/-/CT MSF
Heat-treated
Zn/T/CT (solid) Zn/-/CT MSF
only presented for the samples tested at cryogenic temperature. Additional room-temperature data has been retrieved for comparison from previous publications [17,19e21] for samples with similar foam densities.
3.2. Compression of solid alloys Fig. 2 shows the compressive stress-strain data and light photography of solid A356 aluminium alloy. The cryogenic test data (blue curves) have been obtained for the current study whereas the
room temperature data (yellow curves) have been retrieved from a previous study [20]. It is apparent that testing at cryogenic temperature increases the measured stress values. This stress increase is observed for both the as-cast (full lines) and heat-treated (dashed lines) conditions. At room temperature, A356 exhibits ductile deformation with high levels of plasticity. However, compression at CT changes the deformation to a more brittle mode. Importantly at εz35% a stress drop is observed for the Al/T/CT sample. This behaviour is associated with the formation of a macroscopic shear band, which could clearly be observed in the deformed sample of
Fig. 2. Compressive (a) stress-strain data and (b) photography of solid A356 alloy.
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the “interrupted” compression test (see Fig. 2b). In comparison, only a minor stress drop is registered for the Al/-/CT sample at slightly higher strains. It hence appears that thermal treatment increases the susceptibility of the A356 alloy to cryogenic embrittlement. Fig. 3 shows the compressive stress-strain data of the solid ZA27 alloy. The room temperature data has been retrieved from Ref. [21]. Analogous to A356, higher stresses occur at cryogenic temperatures. In contrast to the more ductile aluminium alloy, as-cast ZA27 undergoes brittle shear fracture at room temperature at ε z30 35%. The deformation sequences for solid ZA27 samples are presented in Fig. 3b. Subject to the heat treatment, it can be easily observed that the Zn/-/CT and Zn/T/CT solid samples exhibit different deformation mechanisms. Heat treatment has successfully been used to increase the ductility of ZA27 at roomtemperature and thus prevent catastrophic shear failure [21]. At cryogenic temperature, all solid ZA27 samples experience brittle failure. However, thermal treatment delays the shear band formation from εz14% (as-cast) to εz21%. 3.3. Compression of metallic syntactic foams Fig. 4 shows the compressive test data for Al MSF. The room temperature data (yellow lines) has been retrieved from a previous study [17] on the same material (sample density range 1.13e1.19 g/ cm3). Similar to the matrix alloy, higher stress values are observed at cryogenic temperature. In the as-cast condition (full lines), the room temperature data indicates a continuous decline of the plateau stress. In comparison, the Al/-/CT samples exhibit a more constant plateau stress with a second peak at ε z45 55%. At cryogenic temperature (blue lines), the heat-treated samples Al/T/ CT exhibit near constant and relatively high plateau stresses up to high strains. As in the case of solid samples, the “interrupted” compression tests at different deformation stages highlight differences in the deformation mechanism (Fig. 4b). The untreated Al/-/ CT MSF samples progressively deform from the upper surface,
while the heat-treated samples develop shear bands at about 45 . Fig. 5 presents the compressive data set for ZA27 MSF. The room temperature data (yellow lines) was retrieved from Ref. [19] for similar samples with a foam density range 1.82e1.87 g/cm3. All curves exhibit an initial stress peak at ε z3 4%. The subsequent stress drop is indicative of macroscopic shear failure. This behaviour mirrors the solid ZA27 behaviour (see Fig. 3) albeit at much lower strains. This deviation can be explained by the localisation of deformation in metallic foams [22,23]. It is of interest that the magnitude of the initial stress peak appears independent of testing temperature and thermal treatment. However, the magnitude of the subsequent stress drop is significantly higher at cryogenic temperature. Images of the deformed samples (see Fig. 5b) present a single catastrophic shear band in the case of Zn/-/CT MSF, leading to the progressive sliding of the two flanks and the very low stresses at high strains. Comparing the cryogenic test data, thermal treatment clearly affects the sample deformation mechanism. From Fig. 5b it can be seen that the Zn/T/CT MSF sample develops multiple shear bands (as opposed to a single catastrophic shear band). Initially, these shear bands do not appear to bisect the entire sample explaining the emergence of a secondary stress peak at ε z20 40%. However, at higher strains these multiple shear bands eventually merge resulting in sample fragmentation. Shear fracture has been previously identified as the dominant failure mechanism of metallic syntactic foams with brittle matrices [24].
4. Discussion Effective MSF properties were determined following ISO13314 standard [18] and are visualized in Fig. 6. Two distinct groups of data points can be distinguished based on the difference in A356 (1.14e1.19 g/cm3) and ZA27 (1.80e1.90 g/cm3) foam densities. In the following, stress-strain data, deformation behaviour and effective material properties are discussed to investigate the effect of testing temperature and thermal treatment for both matrix materials.
Fig. 3. Compressive (a) stress-strain data and (b) photography of solid ZA27 alloy.
T. Fiedler et al. / Journal of Alloys and Compounds 813 (2020) 152181
5
Fig. 4. Compressive (a) stress-strain data and (b) photography of Al MSF.
Fig. 5. Compressive (a) stress-strain data and (b) photography of Zn MSF.
4.1. Aluminium MSF 4.1.1. Heat treatment Solid A356 compression data (see Fig. 2) clearly shows a strength increase of the alloy due to the applied thermal treatment,
i.e. both at room and cryogenic temperatures a distinct stress increase is observed. In the case of aluminium MSF, (see Fig. 4), the heat-treated data is limited to cryogenic temperature. Following the trend of the matrix alloy a distinct strength increase of Al/T/CT MSF is observed in comparison to Al/-/CT MSF. This is further visible
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T. Fiedler et al. / Journal of Alloys and Compounds 813 (2020) 152181
Fig. 6. Effective MSF properties.
in the initial foam strength (Fig. 6a) and plateau stress (Fig. 6b). However, the energy absorption efficiency (Fig. 6c) at cryogenic temperature is not visibly altered by the thermal treatment. The deformation mechanism of solid A356 at cryogenic temperature is shown in Fig. 2b. The as-cast Al/-/CT sample undergoes mostly ductile deformation without any evidence of shear band formation. In contrast, the heat-treated sample Al/T/CT develops a shear band at εz20%: In Fig. 5b, the A356 MSF shows a very similar behaviour, i.e. Al/-/CT MSF undergoes ductile deformation whereas Al/T/CT MSF develops macroscopic shear bands. It can therefore be concluded that the deformation mechanism of Al MSF at cryogenic temperature is controlled by the matrix material.
4.1.2. Testing temperature The solid A356 data further indicates that compression at cryogenic temperature increases A356 deformation resistance compared to room temperature testing. With the exception of a stress drop of Al/T/CT at εz35% distinctly higher stresses are observed for both as-cast and heat-treated conditions. The stress drop is likely associated with the formation of a macroscopic shear band (see Fig. 2b). Considering Fig. 4, only a minor strength increase of as-cast MSF is observed at cryogenic temperature compared to room temperature. This is reflected in a marginal increase of the initial foam strength (Fig. 6a). Analogous to the solid data, Al/-/CT MSF stress then falls below Al/-/RT MSF at ε z20 30%. Comparing the plateau stress of Al/-/CT MSF and Al/-/RT MSF no systematic deviation is apparent (see Fig. 6b) meaning the material property appears unaffected by the testing temperature. Considering the energy absorption efficiency (Fig. 6c), slightly higher values are observed at cryogenic temperature. This is indicative of a more constant plateau stress, which is beneficial to achieve constant accelerations in impact engineering [2].
4.2. Zinc MSF 4.2.1. Heat treatment Considering the solid ZA27 data (Fig. 3) thermal treatment decreases the alloy stresses at room temperature. In contrast, at cryogenic temperature thermal treatment results in a higher first maximum stress. The explanation is an increase in ZA27 ductility due to the thermal treatment that slightly decreases its strength but simultaneously delays the formation of macroscopic shear bands [21]. At room temperature, the strength decrease is predominant as ductile deformation occurs in all solid samples. At cryogenic temperature, brittle failure occurs instead. When reaching its peak stress at εz10%, solid Zn/-/CT actually exhibits slightly higher stresses compared to Zn/T/CT. However, the heat-treated solid sample is further compressed before shear fracture occurs at εz20%. The additional work hardening then causes the higher maximum stress observed for Zn/T/CT. Considering zinc MSF, heat-treated data was limited to cryogenic temperature. The stress-strain data (Fig. 5) show initially very similar curves for Zn/-/CT MSF and Zn/T/CT MSF. This is further reflected in a near identical initial material strength (Fig. 6b). For higher strains ε > 20% a minor deviation occurs. The heat-treated Zinc MSF reaches a slightly higher second stress peak compared to the as-cast MSF. This can be explained by the increased ductility of the matrix material that delays the nucleation and growth of additional shear bands in the foam. In Fig. 6b this is further manifested in an increased plateau stress of Zn/T/CT MSF. It is further of interest to compare the deformation mechanisms of solid ZA27 and zinc MSF. As-cast solid ZA27 suffers a macroscopic shear fracture that rapidly bisects the sample whereas solid Zn/T/CT develops multiple shear bands that only merge and fragment the sample at higher strains (see Fig. 3b). This behaviour is closely mirrored in 5b for ZA27 MSF indicating that the foam deformation
T. Fiedler et al. / Journal of Alloys and Compounds 813 (2020) 152181
mechanism is indeed controlled by the matrix metal. 4.2.2. Testing temperature Solid ZA27 compression data (Fig. 2) clearly shows an increase of the initial foam strength at cryogenic temperature. This coincides with a significant embrittlement of the zinc alloy and both cryogenic tests show a distinct stress-drop that coincides with macroscopic shear fracture of the samples (see Fig. 3b). In contrast, the room temperature tests exhibit a much more ductile deformation and work hardening. Comparing Zn/-/RT MSF and Zn/-/CT MSF (Fig. 5), profound differences in the stress-strain data are observed. However, the initial foam strength appears to be widely independent of thermal treatment (see above) and is near identical for all tested samples (see Fig. 6a). Following this stress peak, the plateau stress gradually increases during room-temperature compression whereas the compressive stress drops to almost 0 MPa at cryogenic temperatures. This deviation can be explained by the brittle fracture of ZA27 at cryogenic conditions that causes MSF fragmentation (see Fig. 5b). As a result, distinctly higher plateau stresses and energy absorption efficiency are obtained for Al/-/RT MSF (Fig. 6b and c). 4.3. Matrix material For both the ZA27 and A356 alloys, the initial strength increases at cryogenic temperature compared to room temperature. However, ZA27 suffers strong embrittlement resulting in catastrophic failure of both solid and MSF samples at higher strains. Therefore, A356 is the superior choice when large material deformation is anticipated, e.g. for controlled energy absorption. In contrast, ZA27 is a viable choice if the initial material strength is of interest. ZA27 MSF exhibits a higher initial strength (see Fig. 6a) that seems widely unaffected by cryogenic conditions. 5. Conclusions Solid and MSF samples were successfully tested at cryogenic temperature (196 C), submerged in a bath of liquid nitrogen. The two solid alloys A356 aluminium and ZA27 zinc and their foams were considered. Where possible, results where compared to room temperature data of the same material retrieved from previous studies. Comparative analysis revealed significant embrittlement of both alloys and of their foams. This effect was more pronounced for the ZA27 alloy. The deformation mechanism of all tested syntactic foams is closely controlled by their matrix alloy. Furthermore, an initial strength increase of the A356 foams was observed at cryogenic temperature. Thermal treatment had previously been applied to increase the ductility of ZA27 at room temperature. However, at cryogenic temperature, the thermal treatment proved ineffective and no significant improvement of MSF foam properties was observed. In contrast, a distinct performance enhancement of the A356 foam at cryogenic temperature was achieved using thermal treatment. Both the initial A356 foam strength and plateau stress increased significantly.
7
Data availability statement The raw/processed data required to reproduce these findings cannot be shared at the time of submission as the data also forms part of an ongoing study. Please contact the corresponding author. References [1] J. Banhart, Manufacture, characterisation and application of cellular metals and metal foams, Prog. Mater. Sci. 46 (6) (2001) 559e632. [2] T. Fiedler, M. Taherishargh, “Large-scale drop test on perliteemetal syntactic foam, J. Compos. Mater. (Jul. 2018), 0021998318786994. €hne, J. Hohe, Applications of aluminum [3] J. Baumeister, J. Weise, E. Hirtz, K. Ho hybrid foam sandwiches in battery housings for electric vehicles, Procedia Mater. Sci. 4 (0) (2014) 317e321. [4] E. Linul, L. Marsavina, J. Kovacik, T. Sadowski, Dynamic and quasi-static compression tests of closed-cell aluminium alloy foams, Proc. Rom. Acad. Ser. A Math. Phys. Tech. Sci. Inf. Sci. 18 (4) (2017) 361e369. [5] B. Ozmat, B. Leyda, B. Benson, Thermal applications of open cell metal foams, Mater. Manuf. Process. 19 (5) (2004) 839e862. [6] F. Garcia-Moreno, Commercial applications of metal foams: their properties and production, Mater. (Basel, Switzerland) 9 (2) (Jan. 2016). [7] M. Yao, et al., LiFePO4-based electrode using micro-porous current collector for high power lithium ion battery, J. Power Sources 173 (1) (2007) 545e549. [8] W. Zhang, et al., Synthesis and mechanism investigation of wide-bandwidth Ni@MnO2 NS foam microwave absorbent, J. Alloy. Comp. 792 (2019) 945e952. [9] E. Linul, D.A. S¸erban, L. Marsavina, L. Sadowski, Assessment of collapse diagrams of rigid polyurethane foams under dynamic loading conditions, Arch. Civ. Mech. Eng. 17 (3) (2017) 457e466. [10] I.A. Chaves, M. Taherishargh, T. Fiedler, “Long-term immersion exposure of perliteealuminium syntactic foam in seawater, J. Compos. Mater. 53 (9) (Aug. 2019) 1229e1240. [11] M. Taherishargh, E. Linul, S. Broxtermann, T. Fiedler, The mechanical properties of expanded perlite-aluminium syntactic foam at elevated temperatures, J. Alloy. Comp. 737 (2018) 590e596. [12] G.L. Golewski, The influence of microcrack width on the mechanical parameters in concrete with the addition of fly ash: Consideration of technological and ecological benefits, Constr. Build. Mater. 197 (2019) 849e861. [13] G.L. Golewski, Effect of fly ash addition on the fracture toughness of plain concrete at third model of fracture, J. Civ. Eng. Manag. 23 (5) (2017) 613e620. [14] T. Dixit, I. Ghosh, Cooling capacity of high porosity open-cell metal foams as passive cryogenic radiators, Cryogenics 84 (2017) 81e88. [15] E. Linul, L. Mars¸avina, P.-A. Linul, J. Kovacik, Cryogenic and high temperature compressive properties of metal foam matrix composites, Compos. Struct. 209 (2019) 490e498. [16] M. Taherishargh, I. V Belova, G.E. Murch, T. Fiedler, Low-density expanded perlite-aluminium syntactic foam, Mater. Sci. Eng. a-Structural Mater. Prop. Microstruct. Process. 604 (2014) 127e134. [17] K. Al-Sahlani, M. Taherishargh, E. Kisi, T. Fiedler, Controlled shrinkage of expanded glass particles in metal syntactic foams, Materials 10 (9) (Sep. 2017) 1073. [18] “ISO13314 Mechanical Testing of Metals d Ductility Testing d Compression Test for Porous and Cellular Metals, 2011. [19] S. Broxtermann, M. Vesenjak, L. Krstulovi c-Opara, T. Fiedler, Quasi static and dynamic compression of zinc syntactic foams, J. Alloy. Comp. 768 (Nov. 2018) 962e969. [20] M. Taherishargh, I.V. Belova, G.E. Murch, T. Fiedler, On the mechanical properties of heat-treated expanded perlite-aluminium syntactic foam, Mater. Des. 63 (2014) 375e383. [21] N. Movahedi, G.E. Murch, I.V. Belova, T. Fiedler, Effect of heat treatment on the compressive behavior of zinc alloy ZA27 syntactic foam, Materials 12 (5) (2019). [22] M. Vesenjak, M.A. Sulong, L. Krstulovi c-Opara, M. Borovinsek, V. Mathier, T. Fiedler, Dynamic compression of aluminium foam derived from infiltration casting of salt dough, Mech. Mater. 93 (Feb. 2016) 96e108. [23] S.A. Meguid, S.S. Cheon, N. El-Abbasi, FE modelling of deformation localizationin metallic foams, Finite Elem. Anal. Des. 38 (7) (2002) 631e643. [24] K. Al-Sahlani, E. Kisi, T. Fiedler, Impact of particle strength and matrix ductility on the deformation mechanism of metallic syntactic foam, J. Alloy. Comp. 786 (25 May 2019) 292e299.
Contents lists available at ScienceDirect
Journal of Alloys and Compounds journal homepage: http://www.elsevier.com/locate/jalcom
Mechanical properties of A356 and ZA27 metallic syntactic foams at cryogenic temperature T. Fiedler a, *, K. Al-Sahlani a, e, P.A. Linul b, c, E. Linul c, d a
The University of Newcastle, School of Engineering, NSW, 2287, Callaghan, Australia Politehnica University of Timisoara, Faculty of Industrial Chemistry and Environmental Engineering, 6 Vasile Parvan Avenue, 300 223, Timisoara, Romania c National Institute of Research for Electrochemistry and Condensed Matter, Aurel Paunescu Podeanu Street 144, 300 569, Timisoara, Romania d Politehnica University of Timisoara, Faculty of Mechanical Engineering, 1 Mihai Viteazu Avenue, 300 222, Timisoara, Romania e The University of Thi-Qar, Engineering Collage, Department of Mechanical Engineering, Nasiriya, Iraq b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 11 June 2019 Received in revised form 3 September 2019 Accepted 5 September 2019 Available online 5 September 2019
This work presents compressions tests of metallic foams at cryogenic temperature. The investigated syntactic foams were manufactured by combining a packed bed of expanded glass particles with either an aluminium or a zinc matrix using infiltration casting. Uni-axial compressions tests were performed after submerging samples in a bath of liquid nitrogen with an equilibrium temperature of 196 C. Both the solid matrix material and syntactic foam samples were tested. For comparison, room temperature reference data from the literature was obtained. In addition, the effect of thermal treatment on the mechanical behaviour of both alloys and their foams at cryogenic temperature was addressed. The results indicate significant embrittlement at cryogenic temperature; however, aluminium and its foams are less susceptible to this effect. © 2019 Elsevier B.V. All rights reserved.
Keywords: Metallic syntactic foam Cryogenic temperature Compressive testing Mechanical properties Deformation mechanisms
1. Introduction Metallic foams are in essence a metallic matrix containing gaseous pores [1]. As a direct result, the relatively high density of the metallic matrices can be reduced. However, their main benefit is the creation of novel properties due to the internal porosity. First, the pores can collapse under load allowing a foam to compress without significant transversal deformation. Paired with a nearconstant deformation resistance, this makes metallic foams attractive for impact protection [2e4]. For interconnected pores, the large internal surface are of the electrically and thermally conductive matrix suggests functional applications such as electrodes, catalysts, heat exchangers, or the absorption of electromagnetic waves [5e8]. Whilst sharing some of these properties with polymer foams [9], metallic foams further exhibit superior resistance to chemically and thermally aggressive environments [10,11]. The inclusion of porous particles has also been successfully pursued for building materials in order to improve environmental sustainability and the mechanical properties of mature concrete
* Corresponding author. E-mail address: thomas.fi[email protected] (T. Fiedler). https://doi.org/10.1016/j.jallcom.2019.152181 0925-8388/© 2019 Elsevier B.V. All rights reserved.
[12,13]. The current study focuses on the use of metallic foams at cryogenic temperatures. Metallic foams may be attractive for cryogenic applications that benefit from large internal surface areas, structural damping, impact protection, and a decreased thermal conductivity. For example, Dixit and Ghosh investigated the usage of aluminium and copper open-cell metal foams for passive cryogenic radiators [14]. They suggested utilization of the large volumetric foam surface area for improved heat rejection to control temperature in space vehicles. To date, little research has been conducted to understand the mechanical behaviour of metallic foams at cryogenic temperatures. Linul et al. [15] investigated the compressive properties of closed cell AlSi10 foam with diamond shaped stainless steel reinforcements. They found superior strength and energy absorption at cryogenic temperature compared to room and elevated (250 C) temperature. These authors further observed a transition of the deformation behaviour of the AlSi10 aluminium matrix from brittle (cryogenic) to ductile at elevated temperature. The current study considers two different matrix metals, i.e. the ZA27 zinc alloy and the A356 aluminium alloy. Metallic syntactic foams (MSF) were manufactured by combining either alloy with porous (~87% particle porosity) glass particles. Half of the produced
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samples were then subjected to thermal treatment to improve the matrix properties whereas the remaining samples were tested in the as-cast condition. Compression testing was performed at cryogenic temperature (~196 C) by submerging the samples in a liquid nitrogen bath. According to author's knowledge, up to now, there are no experimental results with respect to the compressive mechanical behaviour of metallic syntactic foams at cryogenic temperature. Analysis of the obtained test data allows the quantification of mechanical performance at cryogenic conditions. Further comparison with room temperature test data reveals embrittlement of both alloys and their metallic syntactic foams. 2. Methodology
Fig. 1. Samples: ZA27 foam (left), solid ZA27 (centre), A356 foam (right).
2.1. Sample manufacturing All samples were produced using a well-established infiltration casting process [16]. In brief, a packed expanded glass particle bed was confined inside a cylindrical mould. The expanded glass particles were obtained from Dennert Poraver GmbH, Germany and exhibit a diameter rage of 2e2.8 mm with a particle density of 0.33 g/cm3 [17]. The mould was then inserted into a cylindrical crucible with an inner diameter that slightly exceeds the outer mould diameter permitting relative motion of these parts. The crucible contained either ZA27 zinc alloy or A356 aluminium alloy (both obtained from Hayes Metals Pty Ltd, Riverstone NSW, Australia). The nominal chemical compositions of these alloys are presented in Table 1 below. The assembly was then inserted into a furnace and heated to either 530 C (ZA27) or 720 C (A356). Once the metal was completely melted, the assembly was removed from the furnace. A 9.81 N force was applied to push the mould into the crucible and force the melt to infiltrate the voids between the packed particles. Excess melt escaped through a small hole centred in the top of the mould and was subsequently machined to obtain the solid samples. After cooling at atmospheric conditions, samples were manually removed from the crucible. Half of the samples were subjected to thermal treatment to enhance the metallic matrix properties. To this end, the aluminium alloy was solution heattreated at 540 C for 16 h prior to quenching in icy water. Next, these samples were aged for 10 h at 160 C. The ZA27 alloy was solution heat-treated at 365 C for 1 h before quenching. Aging occurred at 140 C for 24 h. All samples were then machined into a cylindrical shape (see Fig. 1) with decreased dimensions for the solid samples due to the 100 kN load cell limit capacity of the testing machine. For simplicity, the following naming convention is adopted in this text: matrix (Al or Zn)/thermal treatment (e or T)/testing temperature (RT or CT), where RT stands for room temperature and CT for cryogenic temperature. As an example Al/-/CT MSF corresponds to an as-cast aluminium foam tested at cryogenic temperature.
min was used in all tests and the main mechanical properties of the investigated samples have been determined according to the international standard ISO13314 [18]. The compressive load and the crosshead displacement were recorded during the tests by using a software embedded in the test machine. Prior to experimental tests and in order to achieve a homogenous temperature distribution in the mass of the samples, both the solid matrix material and metallic syntactic foam samples were submerged and precooled for 20 min at 196 C in a bath of liquid nitrogen. Further, to prevent any temperature reduction after precooling, the samples were held and tested inside the cryogenic device. In order to evaluate the deformation mechanism, a sample from each category was tested “interrupted” at different deformation stages (i.e. 0, 5, 10, 20, 30, 40 and 50% strain). Initially the sample followed the same procedure as outlined above, with the exception that after reaching each deformation stage, the compression test was stopped (first stage at 5% strain), the sample removed from the cryogenic device and photographed. Then, the sample was again submerged and precooled at 196 C for 20 min, and tested to the next stage (10% strain), removed from the device and photographed. This procedure was followed up to a 50% strain, following a 10% strain increment. 2.3. Data evaluation The measured force-displacement data was converted into engineering stress s and strain ε based on the initial sample geometries (see Table 2). All foam data was further processed following ISO13314 to determine effective material properties. Where present the first maximum compressive strength was chosen to quantify the initial material strength, for all remaining samples the 1% offset yield stress was used instead. The plateau stress was calculated as the arithmetic mean between 20% and 40% macroscopic strain. Finally, the energy absorption efficiency was determined to investigate the variation of compressive deformation resistance using
ð 0:5
2.2. Testing Quasi-static uniaxial compression tests were performed on an A009 (LBG TC100) electromechanical computerized universal testing machine, equipped with a maximum compressive load cell capacity of 100 kN. A constant nominal cross-head speed of 10 mm/
Table 1 Chemical alloy compositions (material data sheets). Alloy
Chemical composition
A356 ZA27
7.2 wt% Si, 0.4 wt% Mg, 0.1 wt% Fe, 0.12 wt% Ti, balance Al 27.0 wt% Al, 2.0 wt% Cu, balance Zn
We ¼
0
sdε
0:5,smax
;
where smax is the maximum stress observed up to a strain of ε ¼ 0:5. 3. Results 3.1. Physical properties Table 2 shows the physical properties of all samples manufactured for this study. It should be highlighted that physical data is
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Table 2 Physical properties.
Aluminium A356
As-cast
Designation
Diameter [mm]
Height [mm]
Volume [cm3]
Mass [g]
Density [g/cm3]
Al/-/CT (solid)
17.52 17.45 28.36 28.33 28.34 28.32 17.60 28.34 28.35 28.36 28.29 17.58 17.60 28.35 28.42 28.43 28.40 17.60 17.62 28.40 28.43 28.43 28.40
26.31 26.24 42.34 42.30 42.26 42.40 26.36 42.40 42.32 42.45 42.34 26.37 26.31 42.61 42.42 42.40 42.41 26.33 26.36 42.40 42.40 42.44 42.30
6.34 6.27 26.73 26.65 26.64 26.69 6.41 26.73 26.70 26.80 26.60 6.40 6.40 26.88 26.90 26.90 26.85 6.40 6.42 26.85 26.90 26.93 26.78
16.83 16.44 31.31 30.52 30.37 31.71 16.68 31.44 30.52 31.11 30.19 29.73 30.28 51.06 50.13 49.92 49.54 29.30 30.12 50.98 49.93 49.73 48.75
2.66 2.62 1.17 1.15 1.14 1.19 2.60 1.18 1.14 1.16 1.14 4.65 4.73 1.90 1.86 1.86 1.85 4.65 4.69 1.90 1.86 1.85 1.82
Al/-/CT MSF
Zinc ZA27
Heat-treated
Al/T/CT (solid) Al/T/CT MSF
As-cast
Zn/-/CT (solid) Zn/-/CT MSF
Heat-treated
Zn/T/CT (solid) Zn/-/CT MSF
only presented for the samples tested at cryogenic temperature. Additional room-temperature data has been retrieved for comparison from previous publications [17,19e21] for samples with similar foam densities.
3.2. Compression of solid alloys Fig. 2 shows the compressive stress-strain data and light photography of solid A356 aluminium alloy. The cryogenic test data (blue curves) have been obtained for the current study whereas the
room temperature data (yellow curves) have been retrieved from a previous study [20]. It is apparent that testing at cryogenic temperature increases the measured stress values. This stress increase is observed for both the as-cast (full lines) and heat-treated (dashed lines) conditions. At room temperature, A356 exhibits ductile deformation with high levels of plasticity. However, compression at CT changes the deformation to a more brittle mode. Importantly at εz35% a stress drop is observed for the Al/T/CT sample. This behaviour is associated with the formation of a macroscopic shear band, which could clearly be observed in the deformed sample of
Fig. 2. Compressive (a) stress-strain data and (b) photography of solid A356 alloy.
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the “interrupted” compression test (see Fig. 2b). In comparison, only a minor stress drop is registered for the Al/-/CT sample at slightly higher strains. It hence appears that thermal treatment increases the susceptibility of the A356 alloy to cryogenic embrittlement. Fig. 3 shows the compressive stress-strain data of the solid ZA27 alloy. The room temperature data has been retrieved from Ref. [21]. Analogous to A356, higher stresses occur at cryogenic temperatures. In contrast to the more ductile aluminium alloy, as-cast ZA27 undergoes brittle shear fracture at room temperature at ε z30 35%. The deformation sequences for solid ZA27 samples are presented in Fig. 3b. Subject to the heat treatment, it can be easily observed that the Zn/-/CT and Zn/T/CT solid samples exhibit different deformation mechanisms. Heat treatment has successfully been used to increase the ductility of ZA27 at roomtemperature and thus prevent catastrophic shear failure [21]. At cryogenic temperature, all solid ZA27 samples experience brittle failure. However, thermal treatment delays the shear band formation from εz14% (as-cast) to εz21%. 3.3. Compression of metallic syntactic foams Fig. 4 shows the compressive test data for Al MSF. The room temperature data (yellow lines) has been retrieved from a previous study [17] on the same material (sample density range 1.13e1.19 g/ cm3). Similar to the matrix alloy, higher stress values are observed at cryogenic temperature. In the as-cast condition (full lines), the room temperature data indicates a continuous decline of the plateau stress. In comparison, the Al/-/CT samples exhibit a more constant plateau stress with a second peak at ε z45 55%. At cryogenic temperature (blue lines), the heat-treated samples Al/T/ CT exhibit near constant and relatively high plateau stresses up to high strains. As in the case of solid samples, the “interrupted” compression tests at different deformation stages highlight differences in the deformation mechanism (Fig. 4b). The untreated Al/-/ CT MSF samples progressively deform from the upper surface,
while the heat-treated samples develop shear bands at about 45 . Fig. 5 presents the compressive data set for ZA27 MSF. The room temperature data (yellow lines) was retrieved from Ref. [19] for similar samples with a foam density range 1.82e1.87 g/cm3. All curves exhibit an initial stress peak at ε z3 4%. The subsequent stress drop is indicative of macroscopic shear failure. This behaviour mirrors the solid ZA27 behaviour (see Fig. 3) albeit at much lower strains. This deviation can be explained by the localisation of deformation in metallic foams [22,23]. It is of interest that the magnitude of the initial stress peak appears independent of testing temperature and thermal treatment. However, the magnitude of the subsequent stress drop is significantly higher at cryogenic temperature. Images of the deformed samples (see Fig. 5b) present a single catastrophic shear band in the case of Zn/-/CT MSF, leading to the progressive sliding of the two flanks and the very low stresses at high strains. Comparing the cryogenic test data, thermal treatment clearly affects the sample deformation mechanism. From Fig. 5b it can be seen that the Zn/T/CT MSF sample develops multiple shear bands (as opposed to a single catastrophic shear band). Initially, these shear bands do not appear to bisect the entire sample explaining the emergence of a secondary stress peak at ε z20 40%. However, at higher strains these multiple shear bands eventually merge resulting in sample fragmentation. Shear fracture has been previously identified as the dominant failure mechanism of metallic syntactic foams with brittle matrices [24].
4. Discussion Effective MSF properties were determined following ISO13314 standard [18] and are visualized in Fig. 6. Two distinct groups of data points can be distinguished based on the difference in A356 (1.14e1.19 g/cm3) and ZA27 (1.80e1.90 g/cm3) foam densities. In the following, stress-strain data, deformation behaviour and effective material properties are discussed to investigate the effect of testing temperature and thermal treatment for both matrix materials.
Fig. 3. Compressive (a) stress-strain data and (b) photography of solid ZA27 alloy.
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Fig. 4. Compressive (a) stress-strain data and (b) photography of Al MSF.
Fig. 5. Compressive (a) stress-strain data and (b) photography of Zn MSF.
4.1. Aluminium MSF 4.1.1. Heat treatment Solid A356 compression data (see Fig. 2) clearly shows a strength increase of the alloy due to the applied thermal treatment,
i.e. both at room and cryogenic temperatures a distinct stress increase is observed. In the case of aluminium MSF, (see Fig. 4), the heat-treated data is limited to cryogenic temperature. Following the trend of the matrix alloy a distinct strength increase of Al/T/CT MSF is observed in comparison to Al/-/CT MSF. This is further visible
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Fig. 6. Effective MSF properties.
in the initial foam strength (Fig. 6a) and plateau stress (Fig. 6b). However, the energy absorption efficiency (Fig. 6c) at cryogenic temperature is not visibly altered by the thermal treatment. The deformation mechanism of solid A356 at cryogenic temperature is shown in Fig. 2b. The as-cast Al/-/CT sample undergoes mostly ductile deformation without any evidence of shear band formation. In contrast, the heat-treated sample Al/T/CT develops a shear band at εz20%: In Fig. 5b, the A356 MSF shows a very similar behaviour, i.e. Al/-/CT MSF undergoes ductile deformation whereas Al/T/CT MSF develops macroscopic shear bands. It can therefore be concluded that the deformation mechanism of Al MSF at cryogenic temperature is controlled by the matrix material.
4.1.2. Testing temperature The solid A356 data further indicates that compression at cryogenic temperature increases A356 deformation resistance compared to room temperature testing. With the exception of a stress drop of Al/T/CT at εz35% distinctly higher stresses are observed for both as-cast and heat-treated conditions. The stress drop is likely associated with the formation of a macroscopic shear band (see Fig. 2b). Considering Fig. 4, only a minor strength increase of as-cast MSF is observed at cryogenic temperature compared to room temperature. This is reflected in a marginal increase of the initial foam strength (Fig. 6a). Analogous to the solid data, Al/-/CT MSF stress then falls below Al/-/RT MSF at ε z20 30%. Comparing the plateau stress of Al/-/CT MSF and Al/-/RT MSF no systematic deviation is apparent (see Fig. 6b) meaning the material property appears unaffected by the testing temperature. Considering the energy absorption efficiency (Fig. 6c), slightly higher values are observed at cryogenic temperature. This is indicative of a more constant plateau stress, which is beneficial to achieve constant accelerations in impact engineering [2].
4.2. Zinc MSF 4.2.1. Heat treatment Considering the solid ZA27 data (Fig. 3) thermal treatment decreases the alloy stresses at room temperature. In contrast, at cryogenic temperature thermal treatment results in a higher first maximum stress. The explanation is an increase in ZA27 ductility due to the thermal treatment that slightly decreases its strength but simultaneously delays the formation of macroscopic shear bands [21]. At room temperature, the strength decrease is predominant as ductile deformation occurs in all solid samples. At cryogenic temperature, brittle failure occurs instead. When reaching its peak stress at εz10%, solid Zn/-/CT actually exhibits slightly higher stresses compared to Zn/T/CT. However, the heat-treated solid sample is further compressed before shear fracture occurs at εz20%. The additional work hardening then causes the higher maximum stress observed for Zn/T/CT. Considering zinc MSF, heat-treated data was limited to cryogenic temperature. The stress-strain data (Fig. 5) show initially very similar curves for Zn/-/CT MSF and Zn/T/CT MSF. This is further reflected in a near identical initial material strength (Fig. 6b). For higher strains ε > 20% a minor deviation occurs. The heat-treated Zinc MSF reaches a slightly higher second stress peak compared to the as-cast MSF. This can be explained by the increased ductility of the matrix material that delays the nucleation and growth of additional shear bands in the foam. In Fig. 6b this is further manifested in an increased plateau stress of Zn/T/CT MSF. It is further of interest to compare the deformation mechanisms of solid ZA27 and zinc MSF. As-cast solid ZA27 suffers a macroscopic shear fracture that rapidly bisects the sample whereas solid Zn/T/CT develops multiple shear bands that only merge and fragment the sample at higher strains (see Fig. 3b). This behaviour is closely mirrored in 5b for ZA27 MSF indicating that the foam deformation
T. Fiedler et al. / Journal of Alloys and Compounds 813 (2020) 152181
mechanism is indeed controlled by the matrix metal. 4.2.2. Testing temperature Solid ZA27 compression data (Fig. 2) clearly shows an increase of the initial foam strength at cryogenic temperature. This coincides with a significant embrittlement of the zinc alloy and both cryogenic tests show a distinct stress-drop that coincides with macroscopic shear fracture of the samples (see Fig. 3b). In contrast, the room temperature tests exhibit a much more ductile deformation and work hardening. Comparing Zn/-/RT MSF and Zn/-/CT MSF (Fig. 5), profound differences in the stress-strain data are observed. However, the initial foam strength appears to be widely independent of thermal treatment (see above) and is near identical for all tested samples (see Fig. 6a). Following this stress peak, the plateau stress gradually increases during room-temperature compression whereas the compressive stress drops to almost 0 MPa at cryogenic temperatures. This deviation can be explained by the brittle fracture of ZA27 at cryogenic conditions that causes MSF fragmentation (see Fig. 5b). As a result, distinctly higher plateau stresses and energy absorption efficiency are obtained for Al/-/RT MSF (Fig. 6b and c). 4.3. Matrix material For both the ZA27 and A356 alloys, the initial strength increases at cryogenic temperature compared to room temperature. However, ZA27 suffers strong embrittlement resulting in catastrophic failure of both solid and MSF samples at higher strains. Therefore, A356 is the superior choice when large material deformation is anticipated, e.g. for controlled energy absorption. In contrast, ZA27 is a viable choice if the initial material strength is of interest. ZA27 MSF exhibits a higher initial strength (see Fig. 6a) that seems widely unaffected by cryogenic conditions. 5. Conclusions Solid and MSF samples were successfully tested at cryogenic temperature (196 C), submerged in a bath of liquid nitrogen. The two solid alloys A356 aluminium and ZA27 zinc and their foams were considered. Where possible, results where compared to room temperature data of the same material retrieved from previous studies. Comparative analysis revealed significant embrittlement of both alloys and of their foams. This effect was more pronounced for the ZA27 alloy. The deformation mechanism of all tested syntactic foams is closely controlled by their matrix alloy. Furthermore, an initial strength increase of the A356 foams was observed at cryogenic temperature. Thermal treatment had previously been applied to increase the ductility of ZA27 at room temperature. However, at cryogenic temperature, the thermal treatment proved ineffective and no significant improvement of MSF foam properties was observed. In contrast, a distinct performance enhancement of the A356 foam at cryogenic temperature was achieved using thermal treatment. Both the initial A356 foam strength and plateau stress increased significantly.
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Data availability statement The raw/processed data required to reproduce these findings cannot be shared at the time of submission as the data also forms part of an ongoing study. Please contact the corresponding author. References [1] J. Banhart, Manufacture, characterisation and application of cellular metals and metal foams, Prog. Mater. Sci. 46 (6) (2001) 559e632. [2] T. Fiedler, M. Taherishargh, “Large-scale drop test on perliteemetal syntactic foam, J. Compos. Mater. (Jul. 2018), 0021998318786994. €hne, J. Hohe, Applications of aluminum [3] J. Baumeister, J. Weise, E. Hirtz, K. Ho hybrid foam sandwiches in battery housings for electric vehicles, Procedia Mater. Sci. 4 (0) (2014) 317e321. [4] E. Linul, L. Marsavina, J. Kovacik, T. Sadowski, Dynamic and quasi-static compression tests of closed-cell aluminium alloy foams, Proc. Rom. Acad. Ser. A Math. Phys. Tech. Sci. Inf. Sci. 18 (4) (2017) 361e369. [5] B. Ozmat, B. Leyda, B. Benson, Thermal applications of open cell metal foams, Mater. Manuf. Process. 19 (5) (2004) 839e862. [6] F. Garcia-Moreno, Commercial applications of metal foams: their properties and production, Mater. (Basel, Switzerland) 9 (2) (Jan. 2016). [7] M. Yao, et al., LiFePO4-based electrode using micro-porous current collector for high power lithium ion battery, J. Power Sources 173 (1) (2007) 545e549. [8] W. Zhang, et al., Synthesis and mechanism investigation of wide-bandwidth Ni@MnO2 NS foam microwave absorbent, J. Alloy. Comp. 792 (2019) 945e952. [9] E. Linul, D.A. S¸erban, L. Marsavina, L. Sadowski, Assessment of collapse diagrams of rigid polyurethane foams under dynamic loading conditions, Arch. Civ. Mech. Eng. 17 (3) (2017) 457e466. [10] I.A. Chaves, M. Taherishargh, T. Fiedler, “Long-term immersion exposure of perliteealuminium syntactic foam in seawater, J. Compos. Mater. 53 (9) (Aug. 2019) 1229e1240. [11] M. Taherishargh, E. Linul, S. Broxtermann, T. Fiedler, The mechanical properties of expanded perlite-aluminium syntactic foam at elevated temperatures, J. Alloy. Comp. 737 (2018) 590e596. [12] G.L. Golewski, The influence of microcrack width on the mechanical parameters in concrete with the addition of fly ash: Consideration of technological and ecological benefits, Constr. Build. Mater. 197 (2019) 849e861. [13] G.L. Golewski, Effect of fly ash addition on the fracture toughness of plain concrete at third model of fracture, J. Civ. Eng. Manag. 23 (5) (2017) 613e620. [14] T. Dixit, I. Ghosh, Cooling capacity of high porosity open-cell metal foams as passive cryogenic radiators, Cryogenics 84 (2017) 81e88. [15] E. Linul, L. Mars¸avina, P.-A. Linul, J. Kovacik, Cryogenic and high temperature compressive properties of metal foam matrix composites, Compos. Struct. 209 (2019) 490e498. [16] M. Taherishargh, I. V Belova, G.E. Murch, T. Fiedler, Low-density expanded perlite-aluminium syntactic foam, Mater. Sci. Eng. a-Structural Mater. Prop. Microstruct. Process. 604 (2014) 127e134. [17] K. Al-Sahlani, M. Taherishargh, E. Kisi, T. Fiedler, Controlled shrinkage of expanded glass particles in metal syntactic foams, Materials 10 (9) (Sep. 2017) 1073. [18] “ISO13314 Mechanical Testing of Metals d Ductility Testing d Compression Test for Porous and Cellular Metals, 2011. [19] S. Broxtermann, M. Vesenjak, L. Krstulovi c-Opara, T. Fiedler, Quasi static and dynamic compression of zinc syntactic foams, J. Alloy. Comp. 768 (Nov. 2018) 962e969. [20] M. Taherishargh, I.V. Belova, G.E. Murch, T. Fiedler, On the mechanical properties of heat-treated expanded perlite-aluminium syntactic foam, Mater. Des. 63 (2014) 375e383. [21] N. Movahedi, G.E. Murch, I.V. Belova, T. Fiedler, Effect of heat treatment on the compressive behavior of zinc alloy ZA27 syntactic foam, Materials 12 (5) (2019). [22] M. Vesenjak, M.A. Sulong, L. Krstulovi c-Opara, M. Borovinsek, V. Mathier, T. Fiedler, Dynamic compression of aluminium foam derived from infiltration casting of salt dough, Mech. Mater. 93 (Feb. 2016) 96e108. [23] S.A. Meguid, S.S. Cheon, N. El-Abbasi, FE modelling of deformation localizationin metallic foams, Finite Elem. Anal. Des. 38 (7) (2002) 631e643. [24] K. Al-Sahlani, E. Kisi, T. Fiedler, Impact of particle strength and matrix ductility on the deformation mechanism of metallic syntactic foam, J. Alloy. Comp. 786 (25 May 2019) 292e299.