Effect of Mg-Based Spherical Quasicrystals on Microstructure and Mechanical Properties of ZA85 Alloy

Abstract

To improve the strength-toughness and heat-resistance of die cast magnesium alloy, the ZA85 alloy has been prepared by adding proper amount of spherical quasicrystals containing master alloy. The results indicate that the solidification microstructure is inlaid with quasicrystal particles, which is a new phase i(Mg45Zn47Y5Mn3), co-existing with the α-Mg, Φ(Al2Mg5Zn2) phase and τ(Mg32(AlZn)49) phase. Mechanical properties of ZA85 alloys have been dramatically improved owing to the obvious grain refinement of the matrix microstructure. While adding 1.7 wt % spherical quasicrystal containing master alloy, macro-hardness of ZA85 magnesium alloy reaches 75HB; meanwhile, impact toughness reaches the peak value 18.4Jcm-2, which is about 202% of ZA85 base alloy. Due to the pinning effect of quasicrystal particles on grain boundaries, the strengthened ZA85 alloys would have excellent heat-resistance.

An Overview of Quasicrystal Reinforced Magnesium Metal Matrix Composites

“…Conventional Casting Process. Zhang et al [14] investigated the microstructure and mechanical properties of ZA85 alloy by adding spherically shaped Mg quasicrystal master alloy into the ZA85 magnesium alloy mother melt at 750 0 C. Typical microstructures of the cast ZA85 alloy with various amounts of the SQCM master alloy are shown in fig. 1.…”

“…Hardness and Impact Toughness. The hardness of ZA85 alloy was extensively studied by Zhang et al [14] who found that the high micro hardness and high melting point of quasicrystal phase improves the macro hardness and strength. Fig.…”