- Email: [email protected]
Microstructure and compressive deformation behavior of 2014 aluminium cenosphere syntactic foam made through stircasting technique
Materials Today: Proceedings xxx (xxxx) xxx
Contents lists available at ScienceDirect
Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr
Microstructure and compressive deformation behavior of 2014 aluminium cenosphere syntactic foam made through stircasting technique Sonika Sahu a,⇑, Mohd. Zahid Ansari b, Dehi Pada Mondal c a b c
School of Automation, Banasthali Vidyapith, Niwai 304022, India Mechanical Discipline, PDPM Indian Institute of Information Technology, Design and Manufacturing, Jabalpur 482005, India CSIR-Advanced Materials and Processes Research Institute, Bhopal 462026, India
a r t i c l e
i n f o
Article history: Received 9 March 2019 Received in revised form 22 August 2019 Accepted 9 September 2019 Available online xxxx Keywords: Syntactic foam Compression deformation Microstructure Cenosphere particles Stir casting
a b s t r a c t The present paper deals with manufacturing and characterization of aluminium syntactic foam which was fabricated through stir casting technique. The developed foam was made of 2014 aluminium alloy and 25 vol% of cenosphere particles. The quasi-static compression behavior was studied experimentally at a strain rate of 0.001/s. The fabricated foam shows high strength and a plateau region under compression behavior. The young’s modulus, yield stress, plateau stress and densification strain were quantified and presented. The fabricated foam was also characterized in terms of microstructure to show the cenosphere distribution in aluminium matrix. The microstructure results confirms uniform distribution of cenosphere particle. Ó 2019 Elsevier Ltd. All rights reserved. Peer-review under responsibility of the scientific committee of the 2nd International Conference on Computational and Experimental Methods in Mechanical Engineering.
1. Introduction Aluminium syntactic foam is the one of the class of metal matrix composites, in which hollow spherical particles are reinforced in the aluminium matrix. Reinforcement of the hollow particles in the aluminium matrix leads to form foam with low density along with the enhancement in the physical, mechanical and tribological properties [1–4]. Primarily, these foams could be used in the applications of impact, blast and loading conditions due to high specific strength, excellent stiffness and energy absorption capacity [5–9]. In the recent past, various hollow ceramic particles are evolved commercially for use in the manufacturing of syntactic foam. Silica, alumina, titania, soda lime glass and glass sphere are some of them which are widely used due to benefits of controlled properties such as diameter, size distribution and wall thickness [10,11]. These particles have to pass through various processing steps for ensuring high-quality with narrow distribution of properties. These steps increase the manufacturing cost of hollow particles, which ultimately increase the total production cost of syntactic foams. The production cost may be decreased with use ⇑ Corresponding author. E-mail address: [email protected] (S. Sahu).
of cheaply available cenosphere particles which is obtained from the fly ash, a by-product of coal based power plant and industrial waste [12]. Therefore, cenospheres are more economical than ceramic hollow particles. Cenospheres are lightweight hollow particles, which show high thermal and chemical stability at elevated temperature [13]. Aluminium syntactic foam could be manufactured through various techniques namely stir casting, pressure infiltration and powder metallurgy [14–18]. Among them, stir casting is one of the popular techniques for fabricating the syntactic foam due to low manufacturing cost, easy handling and need of semi-skilled labor. In stir casting process, metal is melted above its liquidus temperature in the furnace and then reinforcement (hollow particles) is added gradually. In order to achieve uniform mixing of reinforcement, the melt is continuously stirred. The prepared mixture is then transferred into the split die and allow for steady cooling at room temperature [2,11–14]. Literature also reports the use of cenosphere particles in the foam fabrication. Balch and Dunand [19] fabricated the 7075 aluminium syntactic foam with silicamullite hollow particles through pressure infiltration method. The compression deformation behavior and load transfer of matrix to cenosphere were analyzed through synchrotron X-ray diffraction. Birla et al. [20] studied the effect of cenosphere content on
https://doi.org/10.1016/j.matpr.2019.09.019 2214-7853/Ó 2019 Elsevier Ltd. All rights reserved. Peer-review under responsibility of the scientific committee of the 2nd International Conference on Computational and Experimental Methods in Mechanical Engineering.
Please cite this article as: S. Sahu, M. Z. Ansari and D. P. Mondal, Microstructure and compressive deformation behavior of 2014 aluminium cenosphere syntactic foam made through stircasting technique, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.019
2
S. Sahu et al. / Materials Today: Proceedings xxx (xxxx) xxx
the compression deformation behavior on aluminium-cenosphere hybrid foam manufactured through stir casting. It was conformed that the mechanical properties were improved upto 30 vol% of cenosphere. Beyond this, there was a reduction in the same. Daoud et al. [21] prepared Pb-Ca-Sn alloy foam reinforced with nickel coated fly ash through stir casting technique. Among all the metal syntactic foam, the lowest specific resistance was obtained in the developed foam. Guo et al. [22] synthesized aluminium syntactic foam by pressure infiltration technique. The obtained results showed the probability of chemical reaction between the cenosphere and aluminium matrix. The aforementioned literature reveals that syntactic foam fabrication through stir casting technique is limited and more research is needed to be carried out in order to understand this in depth. Su et al. [23] fabricated aluminium syntactic foam using aluminium oxide with volume fraction 38–48% through stir casting method. The microstructure and quasi-static compression behavior of foam was analyzed. Therefore, in this paper, 2014 aluminium syntactic foam is fabricated through stir casting method with 25 vol% cenosphere particles reinforcement. The cenosphere particles distribution, microstructure and chemical composition are studied. The compressive stress-strain behavior is studied experimentally at strain rate of 0.001/s. Moreover, the mechanical properties in terms of Young’s modulus, yield stress, plateau stress and densification strain are measured and presented.
Fig. 1. SEM of cenosphere particles before used in fabrication process.
2. Experimental details 2.1. Materials 2014 aluminium alloy and 25 vol% cenosphere particles were used in the fabrication of present foam. The chemical compositions for aluminium alloy and cenosphere are presented in the Table 1. The available average size of cenosphere particles are 100 ± 5 mm as shown in Fig. 1.
Fig. 2. Test samples of fabricated foam.
was characterized for its micro-structural properties like relative density and elemental distribution at cenosphere shell and matrix interface. 2.3. Microstructure characterization
2.2. Material synthesis 2014 aluminium cenosphere syntactic foam was fabricated in the Advanced Materials Processing and Research Institute (AMPRI) Bhopal, India. Firstly, cenosphere particles were preheated at a temperature of 1000–1100 °C and then cooled for 2 h in a furnace for ensuring the removal of carbon content. At the same time, aluminium alloy was melted above the liquidus temperature in the induction furnace. The cenosphere particles were added into at a rate of 100–500 g/min in the melt pool of aluminium alloy. In order to achieve uniform distribution of particles, the melt was stirred at the 600–800 rpm for 5–10 min and then it was transferred into the preheated split die under the application of pressure below 0.5 MPa with the upper punch. The extent of pressure can be varied to make foams of different shapes and sizes. The prepared test samples of fabricated foam are shown in Fig. 2. Finally, the foam Table1 Chemical composition of 2014 aluminium alloy and cenosphere particle. 2014 Aluminium alloy
Chemical composition (wt.%)
Cenosphere particles
Chemical composition (wt.%)
Al Si Fe Cu Mn Mg Cr Zn Ti
93.13 0.76 0.06 4.7 0.78 0.47 0.01 0.06 0.03
SiO2 Al2O3 Fe2O3 TiO2 C
58.3 28.5 6.3 1.2 5.7
The fabricated foam samples were characterized in terms of cenospheres distribution in the aluminium matrix, cenospheres shape and size, chemical composition of the fabricated foam. The prepared foam samples were polished using standard metallographic technique. The polished samples were kept inside the Field Emission Scanning Electron Microscopy (FESEM), (Model: Nova NanoSem 430) and EDS facility (Model: IE synergy 250). 2.4. Compression test Compression test at a strain rate of 0.001/s was performed to mechanical characterized the prepared foam samples. Cubic shape foam samples with the size of 10 10 10 mm were considered. INSTRON 5569 universal testing machine was used to perform the compression testing. The samples were compressed up to 80% strain to observe the behavior in depth. Testing was repeated for three times in order to ensure the accuracy of obtained data. The load-displacement data were recorded during test and then used to convert into compressive stress-strain curves using standard methodology. 3. Result and discussion 3.1. Microstructure The microstructure of investigated aluminium cenosphere syntactic foam is shown in Fig. 3. The cenospheres distribution on the aluminum matrix is shown in Fig. 3(a). The cenospheres size varies
Please cite this article as: S. Sahu, M. Z. Ansari and D. P. Mondal, Microstructure and compressive deformation behavior of 2014 aluminium cenosphere syntactic foam made through stircasting technique, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.019
S. Sahu et al. / Materials Today: Proceedings xxx (xxxx) xxx
3
Fig. 3. (a) Distribution of cenospheres in the aluminum matrix (b) defects on cenosphere particle.
from 90 to 100 mm. Cenospheres inherently contains defects like porosity, non-uniform size and shapes and poor surface finish [13]. The cenosphere characteristics affect the mechanical properties of present syntactic foam in terms of its mechanical strength. Therefore, it is important to analyze the defects available in cenospheres. Fig. 3(b) show high magnification of cenosphere particle. It shows that cenospheres are hollow spherical in nature with uneven shell wall thickness of approximate 5–6 mm. Surface defects (Perforated) are also available on cenosphere which may occur at the time of cenospheres manufacturing or in the aluminium-cenosphere melt during stirring in the electric furnace. The chemical composition of presented foam is shown in Fig. 4, in which the presence of aluminium, silicon and oxygen are observed. 3.2. Compression deformation behavior The compressive deformation behavior and mechanical properties of presented syntactic foam are obtained from compressive stress-strain curve as shown in Fig. 5. Three samples of same density were compressed at 0.001/s showed similar behavior. To characterize the mechanical properties one out of the three curves was taken for analysis as shown in Fig. 5. The curve has been divided into three distinct regions, which is similar to the foam materials [7]. The first region is linear elastic region, in which stress is continuous increases with strain. The slope of linear elastic gives Young’s modulus, which is 5.20 MPa. The limit of elastic behavior and the beginning of plastic behavior gives the yield stress (202.05 MPa) of foam. After the yield stress, foam is deformed plastically known as plateau region (second region). In this region, stress is slightly increase with increased in strain. It shows the limited strain hardening is taken place during the plastic deformation. Similar observation was viewed by some researchers [2,7]. After the plateau region, a densification region (third region) is started, where the foams start solidifies, and in this region, stress increases abruptly with slight increase in strain. Densification strain is 0.49, obtained at the corresponding strain where intersection of tangents are drawn on the plateau and densified regions.
Fig. 5. Compressive stress-strain curves for present foam samples.
4. Conclusion 2014 aluminium cenosphere syntactic foam was fabricated successfully through stir casting technique. The cenospheres with 25 vol% were reinforced in aluminium matrix. Microstructure study and the quasi-static compression were performed on syntactic foam. The concluding remarks drawn are as follows: The fabricated foam density was 2000 kg/m3. The experimental compression tests were performed at a strain rate of 0.001/s to obtained stress-strain curves. The curve exhibited three distinct behaviors of fabricated foam: linear elastic, plateau and densification regions. The yield strength found to be high and plateau region showed the limited strain hardening effect.
Fig. 4. EDS analysis of presented syntactic foam.
Please cite this article as: S. Sahu, M. Z. Ansari and D. P. Mondal, Microstructure and compressive deformation behavior of 2014 aluminium cenosphere syntactic foam made through stircasting technique, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.019
4
S. Sahu et al. / Materials Today: Proceedings xxx (xxxx) xxx
The Young’s modulus was 5.20 MPa, yield stress was 202.05 MPa and densification strain was 0.49. The high magnification images conformed the uniform distribution of cenospheres in the aluminium matrix.
Acknowledgments This study is supported by PDPM IIITDM Jabalpur. References [1] P.K. Rohatgi, J.K. Kim, R.Q. Guo, D.P. Robertson, M. Gajdardziska-Josifovska, Age-hardening characteristics of aluminum alloy-hollow fly ash composites, Metall. Mater. Trans. A: Phys. Metall. Mater. Sci. (2002) 1541–1547. [2] D.P. Mondal, M.D. Goel, V. Upadhyay, S. Das, M. Singh, A.K. Barnwal, Comparative study on microstructural characteristics and compression deformation behaviour of alumina and cenosphere reinforced aluminum syntactic foam made through stir casting technique, Trans. Indian Inst. Met. (2018) 567–577. [3] P.K. Rohatgi, J.K. Kim, N. Gupta, S. Alaraj, A. Daoud, Compressive characteristics of A356/fly ash cenosphere composites synthesized by pressure infiltration technique, Composites Part A: Appl. Sci. Manuf. (2006) 430–437. [4] D.P. Mondal, M.D. Goel, S. Das, Effect of strain rate and relative density on compressive deformation behavior of closed cell aluminum-fly ash composite foam, Mater. Des. (2009) 1268–1274. [5] D.P. Mondal, N. Jha, A. Badkul, S. Das, R. Khedle, High temperature compressive deformation behaviour of aluminum syntactic foam, Mater. Sci. Eng. A (2012) 521–529. [6] I.N. Orbulov, Compressive properties of aluminium matrix syntactic foams, Mater. Sci. Eng. A (2012) 52–56. [7] M.D. Goel, V.A. Matsagar, A.K. Gupta, Blast resistance of stiffened sandwich panels with aluminum cenosphere syntactic foam, Int. J. Impact Eng. (2015) 134–146. [8] Z.Y. Dou, L.T. Jiang, G.H. Wu, Q. Zhang, Z.Y. Xiu, G.Q. Chen, High strain rate compression of cenosphere-pure aluminum syntactic foams, Scr. Mater. (2007) 945–948.
[9] M. Altenaiji, Z.W. Guan, W. Cantwell, Y.Y. Zhao, Characterisation of aluminium matrix syntactic foams dynamic loading, Appl. Mech. Mater. (2014) 296–302. [10] P.K. Rohatgi, N. Gupta, B.F. Schultz, D.D. Luong, The synthesis, compressive properties, and applications of metal matrix syntactic foams, JOM (2011) 36– 42. [11] Manoj, D.M.A. Khan, D.P. Mondal, High temperature deformation behavior of closed cell ZnAl27 hybrid foam made through stir casting technique, Mater. Sci. Eng. A (2018) 324–330. [12] S. Sahu, A.K. Barnwal, D.P. Mondal, P. Jain, ZA27-SiCp composite foam through liquid metallurgy technique using CaH2 as a foaming agent, Indian Foundry J. (2016) 23–29. [13] S. Sahu, M.Z. Ansari, D.P. Mondal, C. Cho, Quasi-static compressive behaviour of aluminium cenosphere syntactic foams, Mater. Sci. Technol. (2019) 856– 864. [14] S. Sahu, M.Z. Ansari, A study on manufacturing processes and compressive properties of zinc-aluminium metal foams, Am. J. Mater. Sci. (2015) 38–42. [15] M. Ahmaruzzaman, A review on the utilization of fly ash, Prog. Energy Combust. Sci. (2010) 327–363. [16] M.Z. Ansari, S. Sahu, M.D. Goel, J.U. Cho, D.P. Mondal, Low-velocity impact characteristics of closed cell AA2014-SiCp composite foam, Composites Part B: Eng. (2018) 394–401. [17] M. Ramachandra, K. Radhakrishna, Synthesis-microstructure-mechanical properties-wear and corrosion behavior of an Al-Si (12%)-Flyash metal matrix composite, J. Mater. Sci. (2005) 5989–5997. [18] X.F. Tao, Y.Y. Zhao, Compressive failure of Al alloy matrix syntactic foams manufactured by melt infiltration, Mater. Sci. Eng. A (2012) 228–232. [19] D.K. Balch, D.C. Dunand, Load partitioning in aluminum syntactic foams containing ceramic microspheres, Acta Mater. (2006) 1501–1511. [20] S. Birla, D.P. Mondal, S. Das, D.K. Kashyap, V.A.N. Ch, Effect of cenosphere content on the compressive deformation behaviour of aluminum-cenosphere hybrid foam, Mater. Sci. Eng. A (2017) 213–226. [21] A. Daoud, M.T.A. El-Khair, A.Y. Shenouda, E. Mohammed, P.K. Rohatgi, Microstructure, tensile properties and electrochemical behavior of Pb alloy45 vol.% fly ash microballoon composites, Mater. Sci. Eng. A (2009) 225–234. [22] R.Q. Guo, P.K. Rohatgi, Chemical reactions between aluminum and fly ash during synthesis and reheating of of Al-fly ash composite, Metall. Mater. Trans. B (1998) 519–525. [23] M. Su, H. Wang, H. Hao, Compressive properties of aluminum matrix syntactic foams prepared by stir casting method, Adv. Eng. Mater. (2019) 1900183.
Please cite this article as: S. Sahu, M. Z. Ansari and D. P. Mondal, Microstructure and compressive deformation behavior of 2014 aluminium cenosphere syntactic foam made through stircasting technique, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.019
Contents lists available at ScienceDirect
Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr
Microstructure and compressive deformation behavior of 2014 aluminium cenosphere syntactic foam made through stircasting technique Sonika Sahu a,⇑, Mohd. Zahid Ansari b, Dehi Pada Mondal c a b c
School of Automation, Banasthali Vidyapith, Niwai 304022, India Mechanical Discipline, PDPM Indian Institute of Information Technology, Design and Manufacturing, Jabalpur 482005, India CSIR-Advanced Materials and Processes Research Institute, Bhopal 462026, India
a r t i c l e
i n f o
Article history: Received 9 March 2019 Received in revised form 22 August 2019 Accepted 9 September 2019 Available online xxxx Keywords: Syntactic foam Compression deformation Microstructure Cenosphere particles Stir casting
a b s t r a c t The present paper deals with manufacturing and characterization of aluminium syntactic foam which was fabricated through stir casting technique. The developed foam was made of 2014 aluminium alloy and 25 vol% of cenosphere particles. The quasi-static compression behavior was studied experimentally at a strain rate of 0.001/s. The fabricated foam shows high strength and a plateau region under compression behavior. The young’s modulus, yield stress, plateau stress and densification strain were quantified and presented. The fabricated foam was also characterized in terms of microstructure to show the cenosphere distribution in aluminium matrix. The microstructure results confirms uniform distribution of cenosphere particle. Ó 2019 Elsevier Ltd. All rights reserved. Peer-review under responsibility of the scientific committee of the 2nd International Conference on Computational and Experimental Methods in Mechanical Engineering.
1. Introduction Aluminium syntactic foam is the one of the class of metal matrix composites, in which hollow spherical particles are reinforced in the aluminium matrix. Reinforcement of the hollow particles in the aluminium matrix leads to form foam with low density along with the enhancement in the physical, mechanical and tribological properties [1–4]. Primarily, these foams could be used in the applications of impact, blast and loading conditions due to high specific strength, excellent stiffness and energy absorption capacity [5–9]. In the recent past, various hollow ceramic particles are evolved commercially for use in the manufacturing of syntactic foam. Silica, alumina, titania, soda lime glass and glass sphere are some of them which are widely used due to benefits of controlled properties such as diameter, size distribution and wall thickness [10,11]. These particles have to pass through various processing steps for ensuring high-quality with narrow distribution of properties. These steps increase the manufacturing cost of hollow particles, which ultimately increase the total production cost of syntactic foams. The production cost may be decreased with use ⇑ Corresponding author. E-mail address: [email protected] (S. Sahu).
of cheaply available cenosphere particles which is obtained from the fly ash, a by-product of coal based power plant and industrial waste [12]. Therefore, cenospheres are more economical than ceramic hollow particles. Cenospheres are lightweight hollow particles, which show high thermal and chemical stability at elevated temperature [13]. Aluminium syntactic foam could be manufactured through various techniques namely stir casting, pressure infiltration and powder metallurgy [14–18]. Among them, stir casting is one of the popular techniques for fabricating the syntactic foam due to low manufacturing cost, easy handling and need of semi-skilled labor. In stir casting process, metal is melted above its liquidus temperature in the furnace and then reinforcement (hollow particles) is added gradually. In order to achieve uniform mixing of reinforcement, the melt is continuously stirred. The prepared mixture is then transferred into the split die and allow for steady cooling at room temperature [2,11–14]. Literature also reports the use of cenosphere particles in the foam fabrication. Balch and Dunand [19] fabricated the 7075 aluminium syntactic foam with silicamullite hollow particles through pressure infiltration method. The compression deformation behavior and load transfer of matrix to cenosphere were analyzed through synchrotron X-ray diffraction. Birla et al. [20] studied the effect of cenosphere content on
https://doi.org/10.1016/j.matpr.2019.09.019 2214-7853/Ó 2019 Elsevier Ltd. All rights reserved. Peer-review under responsibility of the scientific committee of the 2nd International Conference on Computational and Experimental Methods in Mechanical Engineering.
Please cite this article as: S. Sahu, M. Z. Ansari and D. P. Mondal, Microstructure and compressive deformation behavior of 2014 aluminium cenosphere syntactic foam made through stircasting technique, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.019
2
S. Sahu et al. / Materials Today: Proceedings xxx (xxxx) xxx
the compression deformation behavior on aluminium-cenosphere hybrid foam manufactured through stir casting. It was conformed that the mechanical properties were improved upto 30 vol% of cenosphere. Beyond this, there was a reduction in the same. Daoud et al. [21] prepared Pb-Ca-Sn alloy foam reinforced with nickel coated fly ash through stir casting technique. Among all the metal syntactic foam, the lowest specific resistance was obtained in the developed foam. Guo et al. [22] synthesized aluminium syntactic foam by pressure infiltration technique. The obtained results showed the probability of chemical reaction between the cenosphere and aluminium matrix. The aforementioned literature reveals that syntactic foam fabrication through stir casting technique is limited and more research is needed to be carried out in order to understand this in depth. Su et al. [23] fabricated aluminium syntactic foam using aluminium oxide with volume fraction 38–48% through stir casting method. The microstructure and quasi-static compression behavior of foam was analyzed. Therefore, in this paper, 2014 aluminium syntactic foam is fabricated through stir casting method with 25 vol% cenosphere particles reinforcement. The cenosphere particles distribution, microstructure and chemical composition are studied. The compressive stress-strain behavior is studied experimentally at strain rate of 0.001/s. Moreover, the mechanical properties in terms of Young’s modulus, yield stress, plateau stress and densification strain are measured and presented.
Fig. 1. SEM of cenosphere particles before used in fabrication process.
2. Experimental details 2.1. Materials 2014 aluminium alloy and 25 vol% cenosphere particles were used in the fabrication of present foam. The chemical compositions for aluminium alloy and cenosphere are presented in the Table 1. The available average size of cenosphere particles are 100 ± 5 mm as shown in Fig. 1.
Fig. 2. Test samples of fabricated foam.
was characterized for its micro-structural properties like relative density and elemental distribution at cenosphere shell and matrix interface. 2.3. Microstructure characterization
2.2. Material synthesis 2014 aluminium cenosphere syntactic foam was fabricated in the Advanced Materials Processing and Research Institute (AMPRI) Bhopal, India. Firstly, cenosphere particles were preheated at a temperature of 1000–1100 °C and then cooled for 2 h in a furnace for ensuring the removal of carbon content. At the same time, aluminium alloy was melted above the liquidus temperature in the induction furnace. The cenosphere particles were added into at a rate of 100–500 g/min in the melt pool of aluminium alloy. In order to achieve uniform distribution of particles, the melt was stirred at the 600–800 rpm for 5–10 min and then it was transferred into the preheated split die under the application of pressure below 0.5 MPa with the upper punch. The extent of pressure can be varied to make foams of different shapes and sizes. The prepared test samples of fabricated foam are shown in Fig. 2. Finally, the foam Table1 Chemical composition of 2014 aluminium alloy and cenosphere particle. 2014 Aluminium alloy
Chemical composition (wt.%)
Cenosphere particles
Chemical composition (wt.%)
Al Si Fe Cu Mn Mg Cr Zn Ti
93.13 0.76 0.06 4.7 0.78 0.47 0.01 0.06 0.03
SiO2 Al2O3 Fe2O3 TiO2 C
58.3 28.5 6.3 1.2 5.7
The fabricated foam samples were characterized in terms of cenospheres distribution in the aluminium matrix, cenospheres shape and size, chemical composition of the fabricated foam. The prepared foam samples were polished using standard metallographic technique. The polished samples were kept inside the Field Emission Scanning Electron Microscopy (FESEM), (Model: Nova NanoSem 430) and EDS facility (Model: IE synergy 250). 2.4. Compression test Compression test at a strain rate of 0.001/s was performed to mechanical characterized the prepared foam samples. Cubic shape foam samples with the size of 10 10 10 mm were considered. INSTRON 5569 universal testing machine was used to perform the compression testing. The samples were compressed up to 80% strain to observe the behavior in depth. Testing was repeated for three times in order to ensure the accuracy of obtained data. The load-displacement data were recorded during test and then used to convert into compressive stress-strain curves using standard methodology. 3. Result and discussion 3.1. Microstructure The microstructure of investigated aluminium cenosphere syntactic foam is shown in Fig. 3. The cenospheres distribution on the aluminum matrix is shown in Fig. 3(a). The cenospheres size varies
Please cite this article as: S. Sahu, M. Z. Ansari and D. P. Mondal, Microstructure and compressive deformation behavior of 2014 aluminium cenosphere syntactic foam made through stircasting technique, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.019
S. Sahu et al. / Materials Today: Proceedings xxx (xxxx) xxx
3
Fig. 3. (a) Distribution of cenospheres in the aluminum matrix (b) defects on cenosphere particle.
from 90 to 100 mm. Cenospheres inherently contains defects like porosity, non-uniform size and shapes and poor surface finish [13]. The cenosphere characteristics affect the mechanical properties of present syntactic foam in terms of its mechanical strength. Therefore, it is important to analyze the defects available in cenospheres. Fig. 3(b) show high magnification of cenosphere particle. It shows that cenospheres are hollow spherical in nature with uneven shell wall thickness of approximate 5–6 mm. Surface defects (Perforated) are also available on cenosphere which may occur at the time of cenospheres manufacturing or in the aluminium-cenosphere melt during stirring in the electric furnace. The chemical composition of presented foam is shown in Fig. 4, in which the presence of aluminium, silicon and oxygen are observed. 3.2. Compression deformation behavior The compressive deformation behavior and mechanical properties of presented syntactic foam are obtained from compressive stress-strain curve as shown in Fig. 5. Three samples of same density were compressed at 0.001/s showed similar behavior. To characterize the mechanical properties one out of the three curves was taken for analysis as shown in Fig. 5. The curve has been divided into three distinct regions, which is similar to the foam materials [7]. The first region is linear elastic region, in which stress is continuous increases with strain. The slope of linear elastic gives Young’s modulus, which is 5.20 MPa. The limit of elastic behavior and the beginning of plastic behavior gives the yield stress (202.05 MPa) of foam. After the yield stress, foam is deformed plastically known as plateau region (second region). In this region, stress is slightly increase with increased in strain. It shows the limited strain hardening is taken place during the plastic deformation. Similar observation was viewed by some researchers [2,7]. After the plateau region, a densification region (third region) is started, where the foams start solidifies, and in this region, stress increases abruptly with slight increase in strain. Densification strain is 0.49, obtained at the corresponding strain where intersection of tangents are drawn on the plateau and densified regions.
Fig. 5. Compressive stress-strain curves for present foam samples.
4. Conclusion 2014 aluminium cenosphere syntactic foam was fabricated successfully through stir casting technique. The cenospheres with 25 vol% were reinforced in aluminium matrix. Microstructure study and the quasi-static compression were performed on syntactic foam. The concluding remarks drawn are as follows: The fabricated foam density was 2000 kg/m3. The experimental compression tests were performed at a strain rate of 0.001/s to obtained stress-strain curves. The curve exhibited three distinct behaviors of fabricated foam: linear elastic, plateau and densification regions. The yield strength found to be high and plateau region showed the limited strain hardening effect.
Fig. 4. EDS analysis of presented syntactic foam.
Please cite this article as: S. Sahu, M. Z. Ansari and D. P. Mondal, Microstructure and compressive deformation behavior of 2014 aluminium cenosphere syntactic foam made through stircasting technique, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.019
4
S. Sahu et al. / Materials Today: Proceedings xxx (xxxx) xxx
The Young’s modulus was 5.20 MPa, yield stress was 202.05 MPa and densification strain was 0.49. The high magnification images conformed the uniform distribution of cenospheres in the aluminium matrix.
Acknowledgments This study is supported by PDPM IIITDM Jabalpur. References [1] P.K. Rohatgi, J.K. Kim, R.Q. Guo, D.P. Robertson, M. Gajdardziska-Josifovska, Age-hardening characteristics of aluminum alloy-hollow fly ash composites, Metall. Mater. Trans. A: Phys. Metall. Mater. Sci. (2002) 1541–1547. [2] D.P. Mondal, M.D. Goel, V. Upadhyay, S. Das, M. Singh, A.K. Barnwal, Comparative study on microstructural characteristics and compression deformation behaviour of alumina and cenosphere reinforced aluminum syntactic foam made through stir casting technique, Trans. Indian Inst. Met. (2018) 567–577. [3] P.K. Rohatgi, J.K. Kim, N. Gupta, S. Alaraj, A. Daoud, Compressive characteristics of A356/fly ash cenosphere composites synthesized by pressure infiltration technique, Composites Part A: Appl. Sci. Manuf. (2006) 430–437. [4] D.P. Mondal, M.D. Goel, S. Das, Effect of strain rate and relative density on compressive deformation behavior of closed cell aluminum-fly ash composite foam, Mater. Des. (2009) 1268–1274. [5] D.P. Mondal, N. Jha, A. Badkul, S. Das, R. Khedle, High temperature compressive deformation behaviour of aluminum syntactic foam, Mater. Sci. Eng. A (2012) 521–529. [6] I.N. Orbulov, Compressive properties of aluminium matrix syntactic foams, Mater. Sci. Eng. A (2012) 52–56. [7] M.D. Goel, V.A. Matsagar, A.K. Gupta, Blast resistance of stiffened sandwich panels with aluminum cenosphere syntactic foam, Int. J. Impact Eng. (2015) 134–146. [8] Z.Y. Dou, L.T. Jiang, G.H. Wu, Q. Zhang, Z.Y. Xiu, G.Q. Chen, High strain rate compression of cenosphere-pure aluminum syntactic foams, Scr. Mater. (2007) 945–948.
[9] M. Altenaiji, Z.W. Guan, W. Cantwell, Y.Y. Zhao, Characterisation of aluminium matrix syntactic foams dynamic loading, Appl. Mech. Mater. (2014) 296–302. [10] P.K. Rohatgi, N. Gupta, B.F. Schultz, D.D. Luong, The synthesis, compressive properties, and applications of metal matrix syntactic foams, JOM (2011) 36– 42. [11] Manoj, D.M.A. Khan, D.P. Mondal, High temperature deformation behavior of closed cell ZnAl27 hybrid foam made through stir casting technique, Mater. Sci. Eng. A (2018) 324–330. [12] S. Sahu, A.K. Barnwal, D.P. Mondal, P. Jain, ZA27-SiCp composite foam through liquid metallurgy technique using CaH2 as a foaming agent, Indian Foundry J. (2016) 23–29. [13] S. Sahu, M.Z. Ansari, D.P. Mondal, C. Cho, Quasi-static compressive behaviour of aluminium cenosphere syntactic foams, Mater. Sci. Technol. (2019) 856– 864. [14] S. Sahu, M.Z. Ansari, A study on manufacturing processes and compressive properties of zinc-aluminium metal foams, Am. J. Mater. Sci. (2015) 38–42. [15] M. Ahmaruzzaman, A review on the utilization of fly ash, Prog. Energy Combust. Sci. (2010) 327–363. [16] M.Z. Ansari, S. Sahu, M.D. Goel, J.U. Cho, D.P. Mondal, Low-velocity impact characteristics of closed cell AA2014-SiCp composite foam, Composites Part B: Eng. (2018) 394–401. [17] M. Ramachandra, K. Radhakrishna, Synthesis-microstructure-mechanical properties-wear and corrosion behavior of an Al-Si (12%)-Flyash metal matrix composite, J. Mater. Sci. (2005) 5989–5997. [18] X.F. Tao, Y.Y. Zhao, Compressive failure of Al alloy matrix syntactic foams manufactured by melt infiltration, Mater. Sci. Eng. A (2012) 228–232. [19] D.K. Balch, D.C. Dunand, Load partitioning in aluminum syntactic foams containing ceramic microspheres, Acta Mater. (2006) 1501–1511. [20] S. Birla, D.P. Mondal, S. Das, D.K. Kashyap, V.A.N. Ch, Effect of cenosphere content on the compressive deformation behaviour of aluminum-cenosphere hybrid foam, Mater. Sci. Eng. A (2017) 213–226. [21] A. Daoud, M.T.A. El-Khair, A.Y. Shenouda, E. Mohammed, P.K. Rohatgi, Microstructure, tensile properties and electrochemical behavior of Pb alloy45 vol.% fly ash microballoon composites, Mater. Sci. Eng. A (2009) 225–234. [22] R.Q. Guo, P.K. Rohatgi, Chemical reactions between aluminum and fly ash during synthesis and reheating of of Al-fly ash composite, Metall. Mater. Trans. B (1998) 519–525. [23] M. Su, H. Wang, H. Hao, Compressive properties of aluminum matrix syntactic foams prepared by stir casting method, Adv. Eng. Mater. (2019) 1900183.
Please cite this article as: S. Sahu, M. Z. Ansari and D. P. Mondal, Microstructure and compressive deformation behavior of 2014 aluminium cenosphere syntactic foam made through stircasting technique, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.019