Microstructure and Mechanical Properties of Mg-6Zn-1.4Y Alloy Produced by Rheo-Squeeze Casting Process

摘要

Mg-Zn-Y alloys containing a thermally stable icosahedral quasicrystal phase (I-phase) will have wide application future on condition that primary a-Mg dendrite and the I-phase can be refined during the casting process. In this research, the microstructure and mechanical properties of the rheo-squeeze casting (RSC) Mg-6Zn-1.4Y alloys have been investigated. The Mg alloy melt was exposed to ultrasonic vibration (USV) with different acoustic power densities from 0 W/mL to 9 W/mL, and then the slurry was formed by squeeze casting. The results show that good semi-solid slurry with fine and spherical a-Mg particles could be obtained with the acoustic power density of 6 W/mL, and the average grain size and shape factor of primary a-Mg were 32 urn and 0.76, respectively. Meanwhile the coarse eutectic I-phase (Mg_3Zn_6Y) was refined obviously and dispersed uniformly. Compared with the samples without USV, the tensile strength and elongation of the RSC casting samples with 6 W/mL acoustic power density were elevated by 10.6% and 55.5%, respectively.