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An investigation into the microstructure and mechanical properties of V2AlC MAX phase prepared by microwave sintering
Journal of Alloys and Compounds 795 (2019) 291e303
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Journal of Alloys and Compounds journal homepage: http://www.elsevier.com/locate/jalcom
An investigation into the microstructure and mechanical properties of V2AlC MAX phase prepared by microwave sintering Mohsen Hossein-Zadeh a, *, Ehsan Ghasali b, c, Omid Mirzaee a, Hamidreza Mohammadian-Semnani a, Masoud Alizadeh c, Yasin Orooji b, Touradj Ebadzadeh c a b c
Faculty of Materials and Metallurgical Engineering, Semnan University, Semnan, Iran College of Materials Science and Engineering, Nanjing Forestry University, No. 159, Longpan Road, Nanjing, 210037, Jiangsu, People's Republic of China Ceramic Dept, Materials and Energy Research Center, Alborz, Iran
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Article history: Received 17 February 2019 Received in revised form 30 April 2019 Accepted 2 May 2019 Available online 3 May 2019
The present study investigated the mechanical properties and microstructure of V2AlC MAX phase prepared by the microwave sintering process. The powders mixture of the V-Al-C system with the molar ratio of 2:1.5:1 was mixed through a mixer mill for 10 min in the ethanol media without any aggressive milling condition. The microwave sintering process was performed at the sintering temperatures of 1200, 1300 and 1400 C without any soaking times and the protective atmosphere in the graphite bed. The XRD patterns showed the formation of the V2AlC max phase at the sintering temperature of 1200 C with VC and Al2O3 compounds. In contrast, the sample sintered at 1300 C displayed completely matched peaks with the reference pattern of the V2AlC MAX phase. Moreover, the related XRD patterns belonging to the specimen sintered at 1400 C demonstrated the formation of VC and Al2O3 compounds as the dominant crystalline phases. The microstructure studies also showed the formation of the nano-layered MAX phases at the sintering temperatures of 1200 and 1300 C. However, in the case of the sintering temperature of 1400 C, the VC phases turned into the nano-blades shape after the cooling process. The highest bending strength of 189 ± 21 MPa was obtained for the specimen sintered at 1300 C, while the highest Vickers hardness of 892 ± 15 Hv was calculated for the sample sintered at 1400 C as the ceramic composite with the VC-Al2O3 composition. © 2019 Elsevier B.V. All rights reserved.
Keywords: Microstructure V2AlC MAX phase Microwave sintering
1. Introduction MAX phases, as polycrystalline nano-laminates ternary carbides, have attracted great attention due to exhibiting a combination of metallic and ceramic materials properties [1,2]. The general formula of Mnþ1AXn (n ¼ 1, 2 and 3, M ¼ early transition metals, A ¼ A-group element and X ¼ C and/or N), which is known as MAX phases, exhibits a unique combination of properties such as machinability, resistance to thermal shock, oxidation, fatigue and creep, electrical and thermal conductivity, relatively low thermal expansion, etc. Collection of such properties in the MAX phases can make them promising engineering materials in different
* Corresponding author. E-mail addresses: [email protected], M_hosseinzadeh@ semnan.ac.ir (M. Hossein-Zadeh), [email protected], [email protected] (E. Ghasali). https://doi.org/10.1016/j.jallcom.2019.05.029 0925-8388/© 2019 Elsevier B.V. All rights reserved.
applications [3e6]. Depending on the values of n in the MAX phases formula, the M2AX, M3AX2 and M4AX3 phases are typically referred to as 211, 312 and 413 phases, respectively. Experimental or calculated investigations have also shown the formation of the higher order MAX phases such as 514, 615 and 716 [7,8]. Usually, among all different types of prepared MAX phases, the subgroup of 211 is more interesting and has been studied more than other types of the MAX phases [9,10]. V2AlC is a subgroup of the MAX phase in the Al-V-C system which has been studied more than other reported subgroups, such as 312 and 413. C. Hu et al. [11] prepared the V2AlC bulk MAX phase through the in-situ reaction synthesis using the hot pressing method. They found that the molar ratio of 2:1.2:0.9 in the V-Al-C system and also, the sintering temperature of 1400 led to the formation of V2AlC alongside the remained VC and the intermetallic compounds. S. Gupta et al. [12] also studied the synthesis and oxidation behavior of V2AlC. In the case of preparation method,
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they used hot iso-static pressing with an almost complex heat treatment until reaching 1600 C with the soaking time of 8 h at the pressure of 100 MPa. B. Wang et al. [13] also investigated the synthesis and oxidation resistance of V2AlC powders from the initial molar ratio of 2:1.2:1 (V:Al:C) by the molten salt method and the subsequent heat treatment at 1400 C. Moreover, there are some other preparation methods such as melting based on preparing single and/or polycrystalline V2AlC [5,14]. It is worth noting that the literature review shows two fundamental key points in the preparation of the V2AlC MAX phase, especially in the case of the bulk form: 1) using a higher amount of Al rather than the stoichiometric
content, probably due to the Al evaporation at the high temperature, and 2) employing post-heat treatment to eliminate side-effect products and complete the formation reaction by enhancing the diffusion condition [4,15e17]. In the powder metallurgy routes, microwave heating as a pressure-less sintering method offers unique advantages such as a high heating rate, a selective heating zone, efficient internal heating, direct energy supply and penetration, intensified diffusion process and, above all, time and energy saving, in comparison to other conventional methods [18e21]. To the best of authors' knowledge, there is not any research on
Fig. 1. FESEM image of the powders mixture and the corresponding EDS elemental mapping of Al, V and C.
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the preparation of the bulk V2AlC MAX phase prepared by the onestep microwave sintering without any mechanical activation. Moreover, the present study investigated the effect of the sintering temperature on the phase formation, microstructure and mechanical properties of V2AlC MAX phases. 2. Experimental procedures Vanadium (Riedel-de Haen Art. no. 10461 vanadium powder, particle size<50 mm, 99.9% purity) and aluminum (MERCK Art. no. 1056 aluminum powder, particle size<50 mm, 99% purity) and carbon black (purity >95%, average particle size of 150 nm, density 1.86 g/cm3, US Research Nanomaterials Inc., USA) powders were used as the starting materials. The mixture of V-Al-C was prepared with the molar ratio of 2:1.5:1 through the high-energy milling (Spex mixer mill-8000D model) in the Ethanol media for 5 min. The detailed information on the milling process was adopted from the authors' previous work [22]. Then, the mixture was cleaned from the alumina ball and ground at the agate mortar at 70 C until the mixtures were dried completely. The powder mixture was then packed into the steel die for uni-axial cold-pressing under a pressure of 240 MPa to prepare the bar-shaped green bodies with the dimensions of 5 5 25 mm. A self-designed microwave furnace (900 W and 2.45 GHz) with an alumina insulation container was used for the microwave heating. The temperature of the microwave furnace was controlled by an optical pyrometer (RAYR312MSCL2G temperature detector) with the temperature fluctuation of ±5 C. The green bodies were buried at graphite bed and microwave sintering was performed at the maximum power of 900 W for three temperatures of 1200, 1300 and 1400 C without any soaking times. The phase identification was performed using XRD (Philips X0 Pert System) with a Cu ka radiation source and an image-plate detector over the 2q range of 5e85 in the reflection geometry. The porosity of the sintered samples was measured using the Archimedes' principle. The three-point flexural strength test was used to measure the strength of the sintered samples. Vickers microhardness tests were carried out using at least ten successive indentations for each sample by a MKV-h21. Specimens were examined after the grinding and polishing procedure using an FESEM (MIRA 3 TESCAN,
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Czech Republic) equipped with an energy dispersive spectrometer (EDS). 3. Results and discussion Fig. 1 represents the FESEM image and the corresponding EDS elemental mapping of the powders mixture. Regarding Fig. 1, the almost uniform distribution of powders was obtained after milling. It is worth mentioning that the short time of milling did not lead to reducing the particle size of the starting materials. Fig. 2 reveals the XRD patterns of the microwave heated samples at the sintering temperatures of 1200, 1300 and 1400 C. As can be seen, the major peaks in the sintered sample at 1200 C were related to the VC and Al2O3 crystalline phase; also, with the lower priority, the V2AlC phase was formed at this temperature. The XRD pattern of the specimen sintered at 1300 C showed the formation of the V2AlC MAX phase as the dominant peaks and some other peaks with slight intensity that belonged to VC and Al2O3. In contrast, in the case of the higher sintering temperature (1400 C), the XRD results indicated only VC and Al2O3 as the dominant crystalline phases. Obviously, at systems without any oxygen content or with the protective atmosphere, the formation of the low amounts of Al2O3 is related to oxides at the surface of the staring powders of Al and V. However, in the present study, the formation of such high amounts of Al2O3 could be assumed as the external sources, especially from the air atmosphere. The proposed reactions for the formation of V2AlC MAX phase have been studied by many researches; all of them have a good agreement with the following equations [11,23,24]:
V þ 3Al ¼ Al3 V
(1)
4Al þ 3C ¼ Al4 C3
(2)
V þ C ¼ VC
(3)
2V þ Al þ C ¼ V2 AlC
(4)
Fig. 2. XRD patterns of the microwave prepared MAX phases at the sintering temperature of 1200, 1300 and 1400 C.
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Al4 C3 þ 6Al3 V ¼ 3V2 AlC þ 19Al
(5)
7V þ Al4 C3 þ VC ¼ 4V2 AlC
(6)
As it can be seen from Eqs. (1)e(6), the heating process in the AlV-C system could result in the formation of binary intermetallics and carbide between the components; finally the reaction between these binary carbides and intermetallics can formV2AlC [25,26]. However, an interesting question arising is relates to what happens during microwave sintering which leads to the formation of V2AlC at 1300 C; then, by increasing the temperature to 1400 C, why no sign of V2AlC was found in the XRD pattern of the prepared sample
at 1400 C With the highest possibility, with the heating of the VAl-C system at the graphite bed control, the oxygen was diffused from the ambient conditions to the sample. But it seemed that by increasing the temperature, the evaporation of Al (the higher amount of the molar ratio of Al was due to this reason) from the system could be enhanced, destroying the protective layer of the graphite bed. Moreover, it seemed that V2AlC could be produced perfectly at 1300 C; however, after this temperature, the formed V2AlC could be decomposed in getting oxygen, as studied by another research, forming Al2O3 and VC. B. Wang et al. [13] investigated the oxidation behavior of V2AlC in air. They showed that the decomposition of V2AlC was not obvious below 400 C. However, at
Fig. 3. Backscattered FESEM images of the microwave sintered MAX phases at a) 1200 C, b) 1300 C and c) 1400 C.
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Fig. 4. FESEM image and the corresponding elemental mapping of the specimen sintered at 1200 C.
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Fig. 5. FESEM images of the prepared MAX phase at 1200 C with different magnifications at the enlarged regions.
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the higher temperature, the blade-likeV2O5 along-side Al2O3 was the by-product of V2AlC oxidation in the air. So, it could be concluded that in the present study, the optimum temperature of 1300 C led to the perfect formation of V2AlC; the higher temperature led to decomposing V2AlC and breaking the oxidation protective layer of the graphite bed. In the case of the lower temperature, it seemed that the un-reacted intermetallic
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compound or Al staring material adsorbed oxygen and turned to Al2O3, while the formed V2AlC resisted against oxidation, or at least the surface of the formed MAX phase was decomposed [27]. Fig. 3 reveals the FESEM images of the microwave sintered MAX phases at 1200, 1300 and 1400 C. As can be seen, the obtained microstructures of the prepared samples showed two different regions including dark and bright regions. By considering the
Fig. 6. FESEM image and the corresponding elemental mapping of the specimen sintered at 1300 C.
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density of the identified phases at the related XRD pattern of each specimen (Fig. 2), the bright phase at the microstructure of the sintered sample at 1200 C (Fig. 2 a) consisted of the V2AlC MAX phase alongside VC, while the dark area could be assumed as the Al2O3 phase. In the case of the sample sintered at 1300 C, most parts of the microstructure contained a bright region; according to the obtained XRD pattern, it seemed that they belonged to the V2AlC MAX phase. Furthermore, the small amount of microstructure showed a dark region as Al2O3. Finally, the microstructure related to the specimens sintered at 1400 demonstrated the higher amounts of dark phases with some bright phase; the identified crystalline phases from the related XRD patterns in the bright phase
contained mostly the VC phase. However, the literature review reveals that the oxidation phenomenon in V2AlC leads to the formation of V2O5 and Al2O3 [28,29]; however, the XRD pattern and its detection limits only showed the Al2O3 phase. Fig. 4 depicts the FESEM image and the corresponding EDS elemental mapping of the sintered sample at 1200 C. As can be seen from Fig. 4, the bright regions in the presence of Al, V and C could be considered as the V2AlC phase; also, there were some regions in the presence of only two elements of V and C which seemed to contain the VC compound. On the other hand, the dark area in the microstructure showed the presence of Al and O with higher intensities; so, it could be assumed as the Al2O3 phase. It is
Fig. 7. Low magnification back-scattered and secondary electron FESEM images of the prepared specimen at 1300 C.
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worth noting that other phases such as the oxide groups of V and also, some un-reacted intermetallic compounds in the binary system between Al and V could be formed and presented in the microstructure. Fig. 5 shows the FESEM images of the prepared specimen at 1200 C at the bright phases and also, the enlarged areas with a focus on the nano-layered structure of V2AlC. One of the characteristics of the MAX phase is their nano-layered structure, as can be seen in the bright zones of Fig. 5. Moreover, two types of nanolayered structure could be seen: the deformed layered structure and the aligned layers. It seemed that the high heating rate of microwave processing led to expansion and shrinkage within a
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short time, resulting in the formation of areas with deformed and bowed nano-layers of the MAX phases. Also, it seemed that almost good bonding between layers could be realized without delamination and kinks. Fig. 6 exhibits the FESEM image and the corresponding EDS elemental mapping of the specimen sintered at 1300 C. According to the above explanations and configuration of Al, V and C at the demonstrated microstructure in Fig. 6, the bright phases represented the V2AlC MAX phase. Moreover, the dark region with the high intensity of Al in the corresponding EDS elemental mapping could be assumed as Al2O3. Figs. 7 and 8 demonstrate the FESEM images of the sintered sample at 1300 C at relatively low and high
Fig. 8. High magnification back-scattered and secondary electron FESEM images of the prepared specimen at 1300 C.
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Fig. 9. FESEM image and the corresponding elemental mapping of the specimen sintered at 1400 C.
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Fig. 10. FESEM images of the specimen sintered at 1400 C with different magnifications at the selected zone.
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magnifications, respectively. The low magnification secondary and the back-scattered FESEM images at the same area showed that the area with altitude differences as a result of polishing and particle pulling out became darker at the back-scattered images; it seemed that it consisted of V2AlC; however due to the mode of image preparation, it looked like phases with the dark contrast. Fig. 8 represents the high magnification images and the enlarged region focusing on the nano-layered V2AlC ternary carbide. As can be seen from Fig. 8, the characteristic features of the MAX phase as the nano-layered structure seemed to be from the enlarged area, as well as other images in Fig. 8. However, it is worth noting that the ultra-low thickness of this layer was as a result of microwave sintering without any post-heat treatment, soaking time and also, the fast heating rate of this brilliant method. Normally, the soaking time and/or heat-treatment are one of inevitable (needful) procedures to complete the reaction synthesis and densification. However, the microwave sintering process confirmed its ability to prepare the sample at a short time, even without any soaking time. On the other hand, these necessary procedures could lead to growth layers affecting the final properties of the prepared MAX phases [30e33]. Fig. 9 shows the FESEM image and the corresponding EDS elemental mapping of the specimen sintered at 1400 C. As can be seen, the microstructure of the microwave sintered sample at 1400 C demonstrated dark regions as the Al2O3 phase and the bright phase with a high amount of the V element, which seemed to consist of oxidized V alongside VC. For a more detailed investigation, the FESEM images at different magnifications have been presented at Fig. 10. Regarding Fig. 10, the bright regions revealed some reaction products with a needle-like shape. These needle-like phase have been investigated in another research by B. Wang et al. [13] as the V2O5 phase. Moreover, there were some blade-like phases beyond Al2O3 particles which could be attributed to the vanadium oxide-based material. Furthermore, the bright phase at the highest magnification demonstrated an almost layered MAX phase in which oxidation at the high temperature could lead to the decomposition of Al2O3 and V2O5. Table 1 shows the physical and mechanical properties of the microwave sintered samples at 1200, 1300 and 1400 C; these include porosities, Vickers harness and bending strength. As can be seen, the highest bending strength was obtained for the specimens
Table 1 Physical and mechanical properties of the sintered samples at 1200, 1300 and 1400 C. Sintering temperature ( C)
Porosities (%)
Vickers hardness (Hv)
Bending strength (MPa)
1200 1300 1400
2.34 ± 0.6 1.42 ± 0.5 5.31 ± 0.6
512 ± 21 445 ± 18 892 ± 15
134 ± 16 189 ± 21 93 ± 15
sintered at 1300 C; this sample also revealed the lowest porosities. It could be assumed that the oxidation phenomenon affected the porosities of the samples and some exhausting gaseous state of the material from the specimens led to the remaining higher amounts of porosities. Normally, the amounts of porosities have diverse effects on the bending strength; in the present study, increasing the amounts of porosities led to decreasing the bending strength. In the case of hardness, the content of Al2O3 and VC affected the final calculated hardness of the prepared sample. As discussed previously, the sample sintered at 1400 C with the highest amount of Al2O3 showed the highest hardness among all prepared samples. Fig. 11 depicts the force-extension curve during the bending strength test for the prepared sample at the sintering temperatures of 1200, 1300 and 1400 C. The area under these curves could be used as the comparative criteria for the toughness of the samples by absorbing energy before fracture. As can be seen, the specimen sintered at 1300 C revealed the highest fracture load and extension and also, fracture toughness could be taken as the comparative criterion. 4. Conclusion V2AlC MAX phase was prepared successfully through the microwave sintering of the V-Al-C system without any protective atmosphere, milling activation and soaking time as a simple and economical method. Investigation of the effect of the sintering temperature showed that using the final temperature of 1200 C led to the formation of the V2AlC MAX phase with some Al2O3 and VC by-products. In contrast, the sintering temperature of 1400 C led to failing in the preparation of the MAX phase and oxidation problem resulted in the formation of Al2O3 and VC; also, the formed V2AlC was decomposed to oxides of its component at this
Fig. 11. Force-extension curve during the bending strength test of the prepared samples at 1200, 1300 and 1400 C.
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temperature. On the other hand, using 1300 C as the sintering temperature led to preparing the almost uniform structure of the MAX phase with tiny amounts of by-products. The highest bending strength of 189 ± 21 MPa was obtained for the sample sintered at 1300 C with the lowest porosities of 1.42 ± 0.5% among all prepared specimens. Meanwhile, in the case of Vickers hardness, the sample sintered at 1400 C showed the highest amount of 892 ± 15 Hv due to the highest amounts of Al2O3 at the microstructure of this sample. References [1] M. Hossein-Zadeh, O. Mirzaee, H. Mohammadian-Semnani, An investigation into the microstructure and mechanical properties of V4AlC3 MAX phase prepared by spark plasma sintering, Ceram. Int. (2019), https://doi.org/ 10.1016/j.ceramint.2019.01.036. [2] I.-M. Low, Advances in Science and Technology of Mnþ 1AXn Phases, Elsevier, 2012. [3] M.W. Barsoum, M. Radovic, Elastic and mechanical properties of the MAX phases, Annu. Rev. Mater. Res. 41 (2011) 195e227. €gberg, L. Hultman, The Mnþ 1AXn [4] P. Eklund, M. Beckers, U. Jansson, H. Ho phases: materials science and thin-film processing, Thin Solid Films 518 (2010) 1851e1878. [5] L. Shi, T. Ouisse, E. Sarigiannidou, O. Chaix-Pluchery, H. Roussel, D. Chaussende, B. Hackens, Synthesis of single crystals of V2AlC phase by hightemperature solution growth and slow cooling technique, Acta Mater. 83 (2015) 304e309. [6] J. Zhou, S. Gao, Z. Guo, Z. Sun, Ti-enhanced exfoliation of V2AlC into V2C MXene for lithium-ion battery anodes, Ceram. Int. 43 (2017) 11450e11454. [7] Z.M. Sun, Progress in research and development on MAX phases: a family of layered ternary compounds, Int. Mater. Rev. 56 (2011) 143e166. [8] A. Rahman, Z. Rahaman, Study on structural, electronic, optical and mechanical properties of MAX phase compounds and applications, Am. J. Mod. Phys. 4 (2015) 75e91. [9] N. Atazadeh, M.S. Heydari, H.R. Baharvandi, N. Ehsani, Reviewing the effects of different additives on the synthesis of the Ti3SiC2 MAX phase by mechanical alloying technique, Int. J. Refract. Metals Hard Mater. 61 (2016) 67e78. [10] L. Zheng, J. Wang, X. Lu, F. Li, J. Wang, Y. Zhou, (Ti0. 5Nb0. 5) 5AlC4: a newlayered compound belonging to max phases, J. Am. Ceram. Soc. 93 (2010) 3068e3071. [11] C. Hu, L. He, M. Liu, X. Wang, J. Wang, M. Li, Y. Bao, Y. Zhou, In situ reaction synthesis and mechanical properties of V2AlC, J. Am. Ceram. Soc. 91 (2008) 4029e4035. [12] S. Gupta, M.W. Barsoum, Synthesis and oxidation of V 2AlC and (Ti0. 5, V 0.5)2AlC in air, J. Electrochem. Soc. 151 (2004) D24eD29. [13] B. Wang, A. Zhou, Q. Hu, L. Wang, Synthesis and oxidation resistance of V2AlC powders by molten salt method, Int. J. Appl. Ceram. Technol. 14 (2017) 873e879. [14] J. Etzkorn, M. Ade, H. Hillebrecht, V2AlC, V4AlC3-x (xz 0.31), and V12Al3C8: synthesis, crystal growth, structure, and superstructure, Inorg. Chem. 46 (2007) 7646e7653. €gberg, L. Hultman, J. Emmerlich, T. Joelsson, P. Eklund, J.M. Molina[15] H. Ho Aldareguia, J.-P. Palmquist, O. Wilhelmsson, U. Jansson, Growth and characterization of MAX-phase thin films, Surf. Coat. Technol. 193 (2005) 6e10.
303
[16] X. Chen, G. Bei, Toughening mechanisms in nanolayered MAX phase ceramicsda review, Materials (Basel) 10 (2017) 366. n, Magnetic MAX phases from theory and [17] A.S. Ingason, M. Dahlqvist, J. Rose experiments; a review, J. Phys. Condens. Matter 28 (2016) 433003. [18] M. Oghbaei, O. Mirzaee, Microwave versus conventional sintering: a review of fundamentals, advantages and applications, J. Alloys Compd. 494 (2010) 175e189. [19] E. Ghasali, R. Yazdani-rad, A. Rahbari, T. Ebadzadeh, Microwave sintering of aluminum-ZrB2 composite: focusing on microstructure and mechanical properties, Mater. Res. 19 (2016) 765e769, https://doi.org/10.1590/19805373-MR-2015-0799. [20] H. Majidian, E. Ghasali, T. Ebadzadeh, M. Razavi, C. Division, Effect of heating method on microstructure and mechanical properties of zircon reinforced aluminum composites, Mater. Res. 19 (2016) 1443e1448, https://doi.org/ 10.1590/1980-5373-MR-2016-0390. [21] V.G. Karayannis, Microwave sintering of ceramic materials, in: IOP Conf. Ser. Mater. Sci. Eng., IOP Publishing, 2016, p. 12068. [22] E. Ghasali, T. Ebadzadeh, M. Alizadeh, M. Razavi, Spark plasma sintering of WC-based cermets/titanium and vanadium added composites: a comparative study on the microstructure and mechanical properties, Ceram. Int. 44 (2018) 10646e10656, https://doi.org/10.1016/j.ceramint.2018.03.093. [23] M.T. Agne, M. Radovic, G.W. Bentzel, M.W. Barsoum, Stability of V2AlC with Al in 800e1000 C temperature range and in situ synthesis of V2AlC/Al composites, J. Alloys Compd. 666 (2016) 279e286. [24] M.T. Agne, M.W. Barsoum, Enthalpy of formation and thermodynamic parameters of the MAX phase V2AlC, J. Alloys Compd. 665 (2016) 218e224. [25] A. Abdulkadhim, M. To Baben, V. Schnabel, M. Hans, N. Thieme, C. Polzer, P. Polcik, J.M. Schneider, Crystallization kinetics of V2AlC, Thin Solid Films 520 (2012) 1930e1933. [26] M. Hosseinzadeh, O. Mirzaee, H. Mohammadian-Semnani, Evaluation of microstructural and mechanical properties of A356 composite strengthened by nanocrystalline V8C7-Al2O3 particles synthesized through mechanically activated sintering, J. Alloys Compd. 782 (2019) 995e1007. [27] S.R. Kulkarni, M. Merlini, N. Phatak, S.K. Saxena, G. Artioli, S. Gupta, M.W. Barsoum, High temperature thermal expansion and stability of V2AlC up to 950 C, J. Am. Ceram. Soc. 90 (2007) 3013e3016. [28] M. Baben, L. Shang, J. Emmerlich, J.M. Schneider, Oxygen incorporation in M2AlC (M¼ Ti, V, Cr), Acta Mater. 60 (2012) 4810e4818. [29] M.W. Barsoum, MAX Phases: Properties of Machinable Ternary Carbides and Nitrides, John Wiley & Sons, 2013. [30] E. Ghasali, P. Sangpour, A. Jam, H. Rajaei, K. Shirvanimoghaddam, T. Ebadzadeh, Microwave and spark plasma sintering of carbon nanotube and graphene reinforced aluminum matrix composite, Arch. Civ. Mech. Eng. 18 (2018) 1042e1054, https://doi.org/10.1016/j.acme.2018.02.006. [31] S.M.R. Derakhshandeh, M.S. Gohari, E.K. Saeidabadi, A. Jam, H. Rajaei, A. Fazili, M. Alizadeh, E. Ghasali, A. Pakseresht, T. Ebadzadeh, Comparison of spark plasma and microwave sintering of mullite based composite: mullite/Ta2O5 reaction, Ceram. Int. 44 (2018) 13176e13181. [32] E. Ghasali, M. Alizadeh, T. Ebadzadeh, TiO2 ceramic particles-reinforced aluminum matrix composite prepared by conventional, microwave, and spark plasma sintering, J. Compos. Mater. 52 (2018) 2609e2619. [33] E. Ghasali, M. Alizadeh, K. Shirvanimoghaddam, R. Mirzajany, M. Niazmand, A. Faeghi-Nia, T. Ebadzadeh, Porous and non-porous alumina reinforced magnesium matrix composite through microwave and spark plasma sintering processes, Mater. Chem. Phys. 212 (2018), https://doi.org/10.1016/ j.matchemphys.2018.03.058.
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Journal of Alloys and Compounds journal homepage: http://www.elsevier.com/locate/jalcom
An investigation into the microstructure and mechanical properties of V2AlC MAX phase prepared by microwave sintering Mohsen Hossein-Zadeh a, *, Ehsan Ghasali b, c, Omid Mirzaee a, Hamidreza Mohammadian-Semnani a, Masoud Alizadeh c, Yasin Orooji b, Touradj Ebadzadeh c a b c
Faculty of Materials and Metallurgical Engineering, Semnan University, Semnan, Iran College of Materials Science and Engineering, Nanjing Forestry University, No. 159, Longpan Road, Nanjing, 210037, Jiangsu, People's Republic of China Ceramic Dept, Materials and Energy Research Center, Alborz, Iran
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a b s t r a c t
Article history: Received 17 February 2019 Received in revised form 30 April 2019 Accepted 2 May 2019 Available online 3 May 2019
The present study investigated the mechanical properties and microstructure of V2AlC MAX phase prepared by the microwave sintering process. The powders mixture of the V-Al-C system with the molar ratio of 2:1.5:1 was mixed through a mixer mill for 10 min in the ethanol media without any aggressive milling condition. The microwave sintering process was performed at the sintering temperatures of 1200, 1300 and 1400 C without any soaking times and the protective atmosphere in the graphite bed. The XRD patterns showed the formation of the V2AlC max phase at the sintering temperature of 1200 C with VC and Al2O3 compounds. In contrast, the sample sintered at 1300 C displayed completely matched peaks with the reference pattern of the V2AlC MAX phase. Moreover, the related XRD patterns belonging to the specimen sintered at 1400 C demonstrated the formation of VC and Al2O3 compounds as the dominant crystalline phases. The microstructure studies also showed the formation of the nano-layered MAX phases at the sintering temperatures of 1200 and 1300 C. However, in the case of the sintering temperature of 1400 C, the VC phases turned into the nano-blades shape after the cooling process. The highest bending strength of 189 ± 21 MPa was obtained for the specimen sintered at 1300 C, while the highest Vickers hardness of 892 ± 15 Hv was calculated for the sample sintered at 1400 C as the ceramic composite with the VC-Al2O3 composition. © 2019 Elsevier B.V. All rights reserved.
Keywords: Microstructure V2AlC MAX phase Microwave sintering
1. Introduction MAX phases, as polycrystalline nano-laminates ternary carbides, have attracted great attention due to exhibiting a combination of metallic and ceramic materials properties [1,2]. The general formula of Mnþ1AXn (n ¼ 1, 2 and 3, M ¼ early transition metals, A ¼ A-group element and X ¼ C and/or N), which is known as MAX phases, exhibits a unique combination of properties such as machinability, resistance to thermal shock, oxidation, fatigue and creep, electrical and thermal conductivity, relatively low thermal expansion, etc. Collection of such properties in the MAX phases can make them promising engineering materials in different
* Corresponding author. E-mail addresses: [email protected], M_hosseinzadeh@ semnan.ac.ir (M. Hossein-Zadeh), [email protected], [email protected] (E. Ghasali). https://doi.org/10.1016/j.jallcom.2019.05.029 0925-8388/© 2019 Elsevier B.V. All rights reserved.
applications [3e6]. Depending on the values of n in the MAX phases formula, the M2AX, M3AX2 and M4AX3 phases are typically referred to as 211, 312 and 413 phases, respectively. Experimental or calculated investigations have also shown the formation of the higher order MAX phases such as 514, 615 and 716 [7,8]. Usually, among all different types of prepared MAX phases, the subgroup of 211 is more interesting and has been studied more than other types of the MAX phases [9,10]. V2AlC is a subgroup of the MAX phase in the Al-V-C system which has been studied more than other reported subgroups, such as 312 and 413. C. Hu et al. [11] prepared the V2AlC bulk MAX phase through the in-situ reaction synthesis using the hot pressing method. They found that the molar ratio of 2:1.2:0.9 in the V-Al-C system and also, the sintering temperature of 1400 led to the formation of V2AlC alongside the remained VC and the intermetallic compounds. S. Gupta et al. [12] also studied the synthesis and oxidation behavior of V2AlC. In the case of preparation method,
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they used hot iso-static pressing with an almost complex heat treatment until reaching 1600 C with the soaking time of 8 h at the pressure of 100 MPa. B. Wang et al. [13] also investigated the synthesis and oxidation resistance of V2AlC powders from the initial molar ratio of 2:1.2:1 (V:Al:C) by the molten salt method and the subsequent heat treatment at 1400 C. Moreover, there are some other preparation methods such as melting based on preparing single and/or polycrystalline V2AlC [5,14]. It is worth noting that the literature review shows two fundamental key points in the preparation of the V2AlC MAX phase, especially in the case of the bulk form: 1) using a higher amount of Al rather than the stoichiometric
content, probably due to the Al evaporation at the high temperature, and 2) employing post-heat treatment to eliminate side-effect products and complete the formation reaction by enhancing the diffusion condition [4,15e17]. In the powder metallurgy routes, microwave heating as a pressure-less sintering method offers unique advantages such as a high heating rate, a selective heating zone, efficient internal heating, direct energy supply and penetration, intensified diffusion process and, above all, time and energy saving, in comparison to other conventional methods [18e21]. To the best of authors' knowledge, there is not any research on
Fig. 1. FESEM image of the powders mixture and the corresponding EDS elemental mapping of Al, V and C.
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the preparation of the bulk V2AlC MAX phase prepared by the onestep microwave sintering without any mechanical activation. Moreover, the present study investigated the effect of the sintering temperature on the phase formation, microstructure and mechanical properties of V2AlC MAX phases. 2. Experimental procedures Vanadium (Riedel-de Haen Art. no. 10461 vanadium powder, particle size<50 mm, 99.9% purity) and aluminum (MERCK Art. no. 1056 aluminum powder, particle size<50 mm, 99% purity) and carbon black (purity >95%, average particle size of 150 nm, density 1.86 g/cm3, US Research Nanomaterials Inc., USA) powders were used as the starting materials. The mixture of V-Al-C was prepared with the molar ratio of 2:1.5:1 through the high-energy milling (Spex mixer mill-8000D model) in the Ethanol media for 5 min. The detailed information on the milling process was adopted from the authors' previous work [22]. Then, the mixture was cleaned from the alumina ball and ground at the agate mortar at 70 C until the mixtures were dried completely. The powder mixture was then packed into the steel die for uni-axial cold-pressing under a pressure of 240 MPa to prepare the bar-shaped green bodies with the dimensions of 5 5 25 mm. A self-designed microwave furnace (900 W and 2.45 GHz) with an alumina insulation container was used for the microwave heating. The temperature of the microwave furnace was controlled by an optical pyrometer (RAYR312MSCL2G temperature detector) with the temperature fluctuation of ±5 C. The green bodies were buried at graphite bed and microwave sintering was performed at the maximum power of 900 W for three temperatures of 1200, 1300 and 1400 C without any soaking times. The phase identification was performed using XRD (Philips X0 Pert System) with a Cu ka radiation source and an image-plate detector over the 2q range of 5e85 in the reflection geometry. The porosity of the sintered samples was measured using the Archimedes' principle. The three-point flexural strength test was used to measure the strength of the sintered samples. Vickers microhardness tests were carried out using at least ten successive indentations for each sample by a MKV-h21. Specimens were examined after the grinding and polishing procedure using an FESEM (MIRA 3 TESCAN,
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Czech Republic) equipped with an energy dispersive spectrometer (EDS). 3. Results and discussion Fig. 1 represents the FESEM image and the corresponding EDS elemental mapping of the powders mixture. Regarding Fig. 1, the almost uniform distribution of powders was obtained after milling. It is worth mentioning that the short time of milling did not lead to reducing the particle size of the starting materials. Fig. 2 reveals the XRD patterns of the microwave heated samples at the sintering temperatures of 1200, 1300 and 1400 C. As can be seen, the major peaks in the sintered sample at 1200 C were related to the VC and Al2O3 crystalline phase; also, with the lower priority, the V2AlC phase was formed at this temperature. The XRD pattern of the specimen sintered at 1300 C showed the formation of the V2AlC MAX phase as the dominant peaks and some other peaks with slight intensity that belonged to VC and Al2O3. In contrast, in the case of the higher sintering temperature (1400 C), the XRD results indicated only VC and Al2O3 as the dominant crystalline phases. Obviously, at systems without any oxygen content or with the protective atmosphere, the formation of the low amounts of Al2O3 is related to oxides at the surface of the staring powders of Al and V. However, in the present study, the formation of such high amounts of Al2O3 could be assumed as the external sources, especially from the air atmosphere. The proposed reactions for the formation of V2AlC MAX phase have been studied by many researches; all of them have a good agreement with the following equations [11,23,24]:
V þ 3Al ¼ Al3 V
(1)
4Al þ 3C ¼ Al4 C3
(2)
V þ C ¼ VC
(3)
2V þ Al þ C ¼ V2 AlC
(4)
Fig. 2. XRD patterns of the microwave prepared MAX phases at the sintering temperature of 1200, 1300 and 1400 C.
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Al4 C3 þ 6Al3 V ¼ 3V2 AlC þ 19Al
(5)
7V þ Al4 C3 þ VC ¼ 4V2 AlC
(6)
As it can be seen from Eqs. (1)e(6), the heating process in the AlV-C system could result in the formation of binary intermetallics and carbide between the components; finally the reaction between these binary carbides and intermetallics can formV2AlC [25,26]. However, an interesting question arising is relates to what happens during microwave sintering which leads to the formation of V2AlC at 1300 C; then, by increasing the temperature to 1400 C, why no sign of V2AlC was found in the XRD pattern of the prepared sample
at 1400 C With the highest possibility, with the heating of the VAl-C system at the graphite bed control, the oxygen was diffused from the ambient conditions to the sample. But it seemed that by increasing the temperature, the evaporation of Al (the higher amount of the molar ratio of Al was due to this reason) from the system could be enhanced, destroying the protective layer of the graphite bed. Moreover, it seemed that V2AlC could be produced perfectly at 1300 C; however, after this temperature, the formed V2AlC could be decomposed in getting oxygen, as studied by another research, forming Al2O3 and VC. B. Wang et al. [13] investigated the oxidation behavior of V2AlC in air. They showed that the decomposition of V2AlC was not obvious below 400 C. However, at
Fig. 3. Backscattered FESEM images of the microwave sintered MAX phases at a) 1200 C, b) 1300 C and c) 1400 C.
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Fig. 4. FESEM image and the corresponding elemental mapping of the specimen sintered at 1200 C.
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Fig. 5. FESEM images of the prepared MAX phase at 1200 C with different magnifications at the enlarged regions.
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the higher temperature, the blade-likeV2O5 along-side Al2O3 was the by-product of V2AlC oxidation in the air. So, it could be concluded that in the present study, the optimum temperature of 1300 C led to the perfect formation of V2AlC; the higher temperature led to decomposing V2AlC and breaking the oxidation protective layer of the graphite bed. In the case of the lower temperature, it seemed that the un-reacted intermetallic
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compound or Al staring material adsorbed oxygen and turned to Al2O3, while the formed V2AlC resisted against oxidation, or at least the surface of the formed MAX phase was decomposed [27]. Fig. 3 reveals the FESEM images of the microwave sintered MAX phases at 1200, 1300 and 1400 C. As can be seen, the obtained microstructures of the prepared samples showed two different regions including dark and bright regions. By considering the
Fig. 6. FESEM image and the corresponding elemental mapping of the specimen sintered at 1300 C.
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density of the identified phases at the related XRD pattern of each specimen (Fig. 2), the bright phase at the microstructure of the sintered sample at 1200 C (Fig. 2 a) consisted of the V2AlC MAX phase alongside VC, while the dark area could be assumed as the Al2O3 phase. In the case of the sample sintered at 1300 C, most parts of the microstructure contained a bright region; according to the obtained XRD pattern, it seemed that they belonged to the V2AlC MAX phase. Furthermore, the small amount of microstructure showed a dark region as Al2O3. Finally, the microstructure related to the specimens sintered at 1400 demonstrated the higher amounts of dark phases with some bright phase; the identified crystalline phases from the related XRD patterns in the bright phase
contained mostly the VC phase. However, the literature review reveals that the oxidation phenomenon in V2AlC leads to the formation of V2O5 and Al2O3 [28,29]; however, the XRD pattern and its detection limits only showed the Al2O3 phase. Fig. 4 depicts the FESEM image and the corresponding EDS elemental mapping of the sintered sample at 1200 C. As can be seen from Fig. 4, the bright regions in the presence of Al, V and C could be considered as the V2AlC phase; also, there were some regions in the presence of only two elements of V and C which seemed to contain the VC compound. On the other hand, the dark area in the microstructure showed the presence of Al and O with higher intensities; so, it could be assumed as the Al2O3 phase. It is
Fig. 7. Low magnification back-scattered and secondary electron FESEM images of the prepared specimen at 1300 C.
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worth noting that other phases such as the oxide groups of V and also, some un-reacted intermetallic compounds in the binary system between Al and V could be formed and presented in the microstructure. Fig. 5 shows the FESEM images of the prepared specimen at 1200 C at the bright phases and also, the enlarged areas with a focus on the nano-layered structure of V2AlC. One of the characteristics of the MAX phase is their nano-layered structure, as can be seen in the bright zones of Fig. 5. Moreover, two types of nanolayered structure could be seen: the deformed layered structure and the aligned layers. It seemed that the high heating rate of microwave processing led to expansion and shrinkage within a
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short time, resulting in the formation of areas with deformed and bowed nano-layers of the MAX phases. Also, it seemed that almost good bonding between layers could be realized without delamination and kinks. Fig. 6 exhibits the FESEM image and the corresponding EDS elemental mapping of the specimen sintered at 1300 C. According to the above explanations and configuration of Al, V and C at the demonstrated microstructure in Fig. 6, the bright phases represented the V2AlC MAX phase. Moreover, the dark region with the high intensity of Al in the corresponding EDS elemental mapping could be assumed as Al2O3. Figs. 7 and 8 demonstrate the FESEM images of the sintered sample at 1300 C at relatively low and high
Fig. 8. High magnification back-scattered and secondary electron FESEM images of the prepared specimen at 1300 C.
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Fig. 9. FESEM image and the corresponding elemental mapping of the specimen sintered at 1400 C.
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Fig. 10. FESEM images of the specimen sintered at 1400 C with different magnifications at the selected zone.
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magnifications, respectively. The low magnification secondary and the back-scattered FESEM images at the same area showed that the area with altitude differences as a result of polishing and particle pulling out became darker at the back-scattered images; it seemed that it consisted of V2AlC; however due to the mode of image preparation, it looked like phases with the dark contrast. Fig. 8 represents the high magnification images and the enlarged region focusing on the nano-layered V2AlC ternary carbide. As can be seen from Fig. 8, the characteristic features of the MAX phase as the nano-layered structure seemed to be from the enlarged area, as well as other images in Fig. 8. However, it is worth noting that the ultra-low thickness of this layer was as a result of microwave sintering without any post-heat treatment, soaking time and also, the fast heating rate of this brilliant method. Normally, the soaking time and/or heat-treatment are one of inevitable (needful) procedures to complete the reaction synthesis and densification. However, the microwave sintering process confirmed its ability to prepare the sample at a short time, even without any soaking time. On the other hand, these necessary procedures could lead to growth layers affecting the final properties of the prepared MAX phases [30e33]. Fig. 9 shows the FESEM image and the corresponding EDS elemental mapping of the specimen sintered at 1400 C. As can be seen, the microstructure of the microwave sintered sample at 1400 C demonstrated dark regions as the Al2O3 phase and the bright phase with a high amount of the V element, which seemed to consist of oxidized V alongside VC. For a more detailed investigation, the FESEM images at different magnifications have been presented at Fig. 10. Regarding Fig. 10, the bright regions revealed some reaction products with a needle-like shape. These needle-like phase have been investigated in another research by B. Wang et al. [13] as the V2O5 phase. Moreover, there were some blade-like phases beyond Al2O3 particles which could be attributed to the vanadium oxide-based material. Furthermore, the bright phase at the highest magnification demonstrated an almost layered MAX phase in which oxidation at the high temperature could lead to the decomposition of Al2O3 and V2O5. Table 1 shows the physical and mechanical properties of the microwave sintered samples at 1200, 1300 and 1400 C; these include porosities, Vickers harness and bending strength. As can be seen, the highest bending strength was obtained for the specimens
Table 1 Physical and mechanical properties of the sintered samples at 1200, 1300 and 1400 C. Sintering temperature ( C)
Porosities (%)
Vickers hardness (Hv)
Bending strength (MPa)
1200 1300 1400
2.34 ± 0.6 1.42 ± 0.5 5.31 ± 0.6
512 ± 21 445 ± 18 892 ± 15
134 ± 16 189 ± 21 93 ± 15
sintered at 1300 C; this sample also revealed the lowest porosities. It could be assumed that the oxidation phenomenon affected the porosities of the samples and some exhausting gaseous state of the material from the specimens led to the remaining higher amounts of porosities. Normally, the amounts of porosities have diverse effects on the bending strength; in the present study, increasing the amounts of porosities led to decreasing the bending strength. In the case of hardness, the content of Al2O3 and VC affected the final calculated hardness of the prepared sample. As discussed previously, the sample sintered at 1400 C with the highest amount of Al2O3 showed the highest hardness among all prepared samples. Fig. 11 depicts the force-extension curve during the bending strength test for the prepared sample at the sintering temperatures of 1200, 1300 and 1400 C. The area under these curves could be used as the comparative criteria for the toughness of the samples by absorbing energy before fracture. As can be seen, the specimen sintered at 1300 C revealed the highest fracture load and extension and also, fracture toughness could be taken as the comparative criterion. 4. Conclusion V2AlC MAX phase was prepared successfully through the microwave sintering of the V-Al-C system without any protective atmosphere, milling activation and soaking time as a simple and economical method. Investigation of the effect of the sintering temperature showed that using the final temperature of 1200 C led to the formation of the V2AlC MAX phase with some Al2O3 and VC by-products. In contrast, the sintering temperature of 1400 C led to failing in the preparation of the MAX phase and oxidation problem resulted in the formation of Al2O3 and VC; also, the formed V2AlC was decomposed to oxides of its component at this
Fig. 11. Force-extension curve during the bending strength test of the prepared samples at 1200, 1300 and 1400 C.
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temperature. On the other hand, using 1300 C as the sintering temperature led to preparing the almost uniform structure of the MAX phase with tiny amounts of by-products. The highest bending strength of 189 ± 21 MPa was obtained for the sample sintered at 1300 C with the lowest porosities of 1.42 ± 0.5% among all prepared specimens. Meanwhile, in the case of Vickers hardness, the sample sintered at 1400 C showed the highest amount of 892 ± 15 Hv due to the highest amounts of Al2O3 at the microstructure of this sample. References [1] M. Hossein-Zadeh, O. Mirzaee, H. Mohammadian-Semnani, An investigation into the microstructure and mechanical properties of V4AlC3 MAX phase prepared by spark plasma sintering, Ceram. Int. (2019), https://doi.org/ 10.1016/j.ceramint.2019.01.036. [2] I.-M. Low, Advances in Science and Technology of Mnþ 1AXn Phases, Elsevier, 2012. [3] M.W. Barsoum, M. Radovic, Elastic and mechanical properties of the MAX phases, Annu. Rev. Mater. Res. 41 (2011) 195e227. €gberg, L. Hultman, The Mnþ 1AXn [4] P. Eklund, M. Beckers, U. Jansson, H. Ho phases: materials science and thin-film processing, Thin Solid Films 518 (2010) 1851e1878. [5] L. Shi, T. Ouisse, E. Sarigiannidou, O. Chaix-Pluchery, H. Roussel, D. Chaussende, B. Hackens, Synthesis of single crystals of V2AlC phase by hightemperature solution growth and slow cooling technique, Acta Mater. 83 (2015) 304e309. [6] J. Zhou, S. Gao, Z. Guo, Z. Sun, Ti-enhanced exfoliation of V2AlC into V2C MXene for lithium-ion battery anodes, Ceram. Int. 43 (2017) 11450e11454. [7] Z.M. Sun, Progress in research and development on MAX phases: a family of layered ternary compounds, Int. Mater. Rev. 56 (2011) 143e166. [8] A. Rahman, Z. Rahaman, Study on structural, electronic, optical and mechanical properties of MAX phase compounds and applications, Am. J. Mod. Phys. 4 (2015) 75e91. [9] N. Atazadeh, M.S. Heydari, H.R. Baharvandi, N. Ehsani, Reviewing the effects of different additives on the synthesis of the Ti3SiC2 MAX phase by mechanical alloying technique, Int. J. Refract. Metals Hard Mater. 61 (2016) 67e78. [10] L. Zheng, J. Wang, X. Lu, F. Li, J. Wang, Y. Zhou, (Ti0. 5Nb0. 5) 5AlC4: a newlayered compound belonging to max phases, J. Am. Ceram. Soc. 93 (2010) 3068e3071. [11] C. Hu, L. He, M. Liu, X. Wang, J. Wang, M. Li, Y. Bao, Y. Zhou, In situ reaction synthesis and mechanical properties of V2AlC, J. Am. Ceram. Soc. 91 (2008) 4029e4035. [12] S. Gupta, M.W. Barsoum, Synthesis and oxidation of V 2AlC and (Ti0. 5, V 0.5)2AlC in air, J. Electrochem. Soc. 151 (2004) D24eD29. [13] B. Wang, A. Zhou, Q. Hu, L. Wang, Synthesis and oxidation resistance of V2AlC powders by molten salt method, Int. J. Appl. Ceram. Technol. 14 (2017) 873e879. [14] J. Etzkorn, M. Ade, H. Hillebrecht, V2AlC, V4AlC3-x (xz 0.31), and V12Al3C8: synthesis, crystal growth, structure, and superstructure, Inorg. Chem. 46 (2007) 7646e7653. €gberg, L. Hultman, J. Emmerlich, T. Joelsson, P. Eklund, J.M. Molina[15] H. Ho Aldareguia, J.-P. Palmquist, O. Wilhelmsson, U. Jansson, Growth and characterization of MAX-phase thin films, Surf. Coat. Technol. 193 (2005) 6e10.
303
[16] X. Chen, G. Bei, Toughening mechanisms in nanolayered MAX phase ceramicsda review, Materials (Basel) 10 (2017) 366. n, Magnetic MAX phases from theory and [17] A.S. Ingason, M. Dahlqvist, J. Rose experiments; a review, J. Phys. Condens. Matter 28 (2016) 433003. [18] M. Oghbaei, O. Mirzaee, Microwave versus conventional sintering: a review of fundamentals, advantages and applications, J. Alloys Compd. 494 (2010) 175e189. [19] E. Ghasali, R. Yazdani-rad, A. Rahbari, T. Ebadzadeh, Microwave sintering of aluminum-ZrB2 composite: focusing on microstructure and mechanical properties, Mater. Res. 19 (2016) 765e769, https://doi.org/10.1590/19805373-MR-2015-0799. [20] H. Majidian, E. Ghasali, T. Ebadzadeh, M. Razavi, C. Division, Effect of heating method on microstructure and mechanical properties of zircon reinforced aluminum composites, Mater. Res. 19 (2016) 1443e1448, https://doi.org/ 10.1590/1980-5373-MR-2016-0390. [21] V.G. Karayannis, Microwave sintering of ceramic materials, in: IOP Conf. Ser. Mater. Sci. Eng., IOP Publishing, 2016, p. 12068. [22] E. Ghasali, T. Ebadzadeh, M. Alizadeh, M. Razavi, Spark plasma sintering of WC-based cermets/titanium and vanadium added composites: a comparative study on the microstructure and mechanical properties, Ceram. Int. 44 (2018) 10646e10656, https://doi.org/10.1016/j.ceramint.2018.03.093. [23] M.T. Agne, M. Radovic, G.W. Bentzel, M.W. Barsoum, Stability of V2AlC with Al in 800e1000 C temperature range and in situ synthesis of V2AlC/Al composites, J. Alloys Compd. 666 (2016) 279e286. [24] M.T. Agne, M.W. Barsoum, Enthalpy of formation and thermodynamic parameters of the MAX phase V2AlC, J. Alloys Compd. 665 (2016) 218e224. [25] A. Abdulkadhim, M. To Baben, V. Schnabel, M. Hans, N. Thieme, C. Polzer, P. Polcik, J.M. Schneider, Crystallization kinetics of V2AlC, Thin Solid Films 520 (2012) 1930e1933. [26] M. Hosseinzadeh, O. Mirzaee, H. Mohammadian-Semnani, Evaluation of microstructural and mechanical properties of A356 composite strengthened by nanocrystalline V8C7-Al2O3 particles synthesized through mechanically activated sintering, J. Alloys Compd. 782 (2019) 995e1007. [27] S.R. Kulkarni, M. Merlini, N. Phatak, S.K. Saxena, G. Artioli, S. Gupta, M.W. Barsoum, High temperature thermal expansion and stability of V2AlC up to 950 C, J. Am. Ceram. Soc. 90 (2007) 3013e3016. [28] M. Baben, L. Shang, J. Emmerlich, J.M. Schneider, Oxygen incorporation in M2AlC (M¼ Ti, V, Cr), Acta Mater. 60 (2012) 4810e4818. [29] M.W. Barsoum, MAX Phases: Properties of Machinable Ternary Carbides and Nitrides, John Wiley & Sons, 2013. [30] E. Ghasali, P. Sangpour, A. Jam, H. Rajaei, K. Shirvanimoghaddam, T. Ebadzadeh, Microwave and spark plasma sintering of carbon nanotube and graphene reinforced aluminum matrix composite, Arch. Civ. Mech. Eng. 18 (2018) 1042e1054, https://doi.org/10.1016/j.acme.2018.02.006. [31] S.M.R. Derakhshandeh, M.S. Gohari, E.K. Saeidabadi, A. Jam, H. Rajaei, A. Fazili, M. Alizadeh, E. Ghasali, A. Pakseresht, T. Ebadzadeh, Comparison of spark plasma and microwave sintering of mullite based composite: mullite/Ta2O5 reaction, Ceram. Int. 44 (2018) 13176e13181. [32] E. Ghasali, M. Alizadeh, T. Ebadzadeh, TiO2 ceramic particles-reinforced aluminum matrix composite prepared by conventional, microwave, and spark plasma sintering, J. Compos. Mater. 52 (2018) 2609e2619. [33] E. Ghasali, M. Alizadeh, K. Shirvanimoghaddam, R. Mirzajany, M. Niazmand, A. Faeghi-Nia, T. Ebadzadeh, Porous and non-porous alumina reinforced magnesium matrix composite through microwave and spark plasma sintering processes, Mater. Chem. Phys. 212 (2018), https://doi.org/10.1016/ j.matchemphys.2018.03.058.