Changes in Grain Size, Texture, and Mechanical Properties of AZ31/(TiO2)p Nanocomposites Processed by Isothermal Multidirectional Forging

Document Type : Original Research Paper


Mechanical Engineering Department, Faculty of Engineering, Malayer University, Malayer, Iran.


In the current study, magnesium-matrix AZ31/ 1.5 vol.% (TiO2)p nanocomposites manufactured using stir casting underwent extrusion process. The as-cast ingots were extruded, then processed by multidirectional forging (MDF) up to 8 passes at constant temperature of 320C. Investigating microstructures showed that after the second pass, the size of matrix grains underwent a significant decrease. However, this decrease didn’t continue in subsequent passes and grain size increased at the fourth pass. In the sixth pass, grain size decreased again, resulting in the smallest microstructure in all the samples. However, in the last two passes, grain size increased similar
to the case of the fourth pass. The results of shear punch and Vickers’ microhardness tests showed that changes in shear yield strength, ultimate shear strength, and hardness followed a similar trend. Furthermore, the results of these tests showed that the best mechanical properties are observed
in the first two passes after which no further improvement is observed in shear strength and hardness of the samples while fourth, sixth, and eighth passes resulted in better mechanical properties compared to the extruded sample. 


[1] J. Fan, H. Zhang, H. Dong, B. Xu, Z. Zhang, L. Shi, Effects of processing technologies on mechanical properties of SiC particulate reinforced magnesium matrix composites, J. Wuhan Uni. Technol. Mater. Sci. Ed., 29(4) (2014) 769-772.
[2] Q.B. Nguyen, K.S. Tun, C.Y.H. Lim, W.L.E. Wong, M. Gupta, Influence of nano-alumina and sub-micron copper on mechanical properties of magnesium alloy AZ31, Compos. Part B-Eng., 55 (2013) 486-491.
[3] X.J. Wang, K.B. Nie, X.J. Sa, X.S. Hu, K. Wu, M.Y. Zheng, Microstructure and mechanical properties of SiCp/Mg-Zn-Ca composites fabricated by stir casting, Mater. Sci. Eng. A, 534 (2012) 60-67.
[4] X.G. Qiao, T. Ying, M.Y. Zheng, E.D. Wei, K. Wu, X.S. Hu, W.M. Gan, H.G. Brokmeier, I.S. Golovin, Microstructure evolution and mechanical properties of nano-SiCp/AZ91 composite processed by extrusion and equal channel angular pressing (ECAP), Mater. Charact., 121 (2016) 222-230.
[5] M. Rashad, F. Pan, Y. Liu, X. Chen, H. Lin, R. Pan, M. Asif, J. She, High temperature formability of graphene nanoplatelets-AZ31 composites fabricated by stir-casting method, J. Magnesium Alloys, 4(4) (2016) 270-277.
[6] M.J. Shen, X.J Wang, T. Ying, K. Wu, W.J. Song, Characteristics and mechanical properties of magnesium matrix composites reinforced with micron/submicron/nano SiC particles, J. Alloys Compd., 686 (2016) 831-840.
[7] K.B. Nie, K.K. Deng, X.J. Wang, T. Wang, K. Wu, Influence of SiC nanoparticles addition on the
microstructural evolution and mechanical properties of AZ91 alloy during isothermal multidirectional forging, Mater. Charact., 124 (2017) 14-24.
[8] K. Nie, X. Wang, X. Hu, Y. Wu, K. Deng, K. Wu, M. Zheng, Effect of multidirectional forging on microstructures and tensile properties of a particulate reinforced magnesium matrix composite, Mater. Sci. Eng. A, 528(24) (2011) 7133-7139.
[9] P. Poddar, V.C. Srivastava, P.K. De, K.L. Sahoo, Processing and mechanical properties of SiC reinforced cast magnesium matrix composites by stir casting process, Mater. Sci. Eng. A, 460-461
(2007) 357-364.
[10] M.J. Shen, X.J. Wang, C.D. Li, M.F. Zhang, X.S. Hu, M.Y. Zheng, K. Wu, Effect of submicron size
SiC particles on microstructure and mechanical properties of AZ31B magnesium matrix composites, Mater. Des., (1980-2015), 54 (2014) 436-442.
[11] K.B. Nie, K. Wu, X.J. Wang, K.K. Deng, Y.W. Wu, M.Y. Zheng, Multidirectional forging of magnesium matrix composites: effect on microstructures and tensile properties, Mater. Sci. Eng. A, 527(27-28) (2010) 7364-7368.
[12] K. Wu, K. Deng, K. Nie, Y. Wu, X. Wang, X. Hu, M. Zheng, Microstructure and mechanical properties of SiCp/AZ91 composite deformed through a combination of forging and extrusion process, Mater. Des., 31(8) (2010) 3929-3932.
[13] X.J. Wang, K. Wu, H.F. Zhang, W.X. Huang, H. Chang, W.M. Gan, M.Y. Zheng, D.L. Peng, Effect of hot extrusion on the microstructure of a particulate reinforced magnesium matrix composite, Mater. Sci. Eng. A, 465(1-2) (2007) 78-84.
[14] A. Azushima, R. Kopp, A. Korhonen, D.Y. Yang, F. Micari, G.D. Lahoti, P. Groche, J. Yanagimoto, N. Tsuji, A. Rosochowski, A. Yanagida, Severe plastic deformation (SPD) processes for metals, CIRP Annals, 57(2) (2008) 716-735.
[15] A. Salandari-Rabori, A. Zarei-Hanzaki, S.M. Fatemi, M. Ghambari, M. Moghaddam, Microstructure and superior mechanical properties of a multi-axially forged WE magnesium alloy, J. Alloys Compd., 693 (2017) 406-413.
[16] R. Alizadeh, R. Mahmudi, O.A. Ruano, A.H.W. Ngan, Constitutive Analysis and Hot Deformation Behavior of Fine-Grained Mg-Gd-Y-Zr Alloys, Metall. Mater. Trans. A, 48(11) (2017) 5699-5709.
[17] M. Habibnejad-Korayem, R. Mahmudi, W.J. Poole, Enhanced properties of Mg-based nanocomposites reinforced with Al2O3 nano-particles, Mater. Sci. Eng. A, 519(1-2) (2009) 198-203.
[18] W. Liao, B. Ye, L. Zhang, H. Zhou, W. Guo, Q. Wang, W. Li, Microstructure evolution and mechanical properties of SiC nanoparticles reinforced magnesium matrix composite processed by cyclic closed-die forging, Mater. Sci. Eng. A, 642 (2015) 49-56.
[19] K.B. Nie, K.K. Deng, X.J. Wang, W.M. Gan, F.J. Xu, K. Wu, M.Y. Zheng, Microstructures and mechanical properties of SiCp/AZ91 magnesium matrix nanocomposites processed by multidirectional
forging, J. Alloys Compd., 622 (2015) 1018-1026.
[20] S.J. Huang, C. H. Ho, Y. Feldman, R. Tenne, Advanced AZ31 Mg alloy composites reinforced by
WS2 nanotubes, J. Alloys Compd., 654 (2016) 15-22.
[21] F. Akbaripanah, F. Fereshteh-Saniee, R. Mahmudi, H.K. Kim, Microstructural homogeneity, texture, tensile and shear behavior of AM60 magnesium alloy produced by extrusion and equal channel angular pressing, Mater. Des., 43 (2013)31-39.