Zn与Al质量比对Mg-Zn-Al三元镁合金铸态组织和凝固行为的影响

Effect of mass ratio of Zn to Al on as-cast microstructure and solidification behaviour of Mg-Zn-Al ternary magnesium alloys

研究了Zn与Al质量比对Mg-Zn-Al三元镁合金铸态组织和凝固行为的影响。结果表明:Zn与Al质量比小于2的实验合金主要由α-Mg+Mg32(Al,Zn)49相组成,且随着Zn与Al质量比的增加,实验合金中第二相的数量逐渐减少,同时其分布由连续网状逐渐向断续状转变;Zn与Al质量比大于2的实验合金则主要由α-Mg+Mg32(Al,Zn)49+MgZn相组成,且随着Zn与Al质量比的增加,实验合金中第二相的数量逐渐增加,同时其分布由断续网状逐渐向颗粒弥散状转变;此外,Zn与Al质量比小于2的实验合金的第二相转变开始温度和峰值温度基本上高于Zn与Al质量比大于2的实验合金,从而导致第二相转变过程中不同相变的发生和第二相类型的不同。

The effect of mass ratio of Zn to Al on the as-cast microstructure and solidification behaviour of Mg-Zn-Al ternary magnesium alloys was investigated. The results indicate that, when the mass ratio of Zn to Al of experimental alloys are less than 2, the alloys are composed of α-Mg and Mg32（Al, Zn）49 phases, and with increasing mass ratio of Zn to Al, the amount of the second phases in the alloys gradually decreases and the distribution of the second phases changes from continuous net to quasti-continuous net. However, when the mass ratio of Zn to Al of experimental alloys is more than 2, the alloys are composed of α-Mg, Mg32（Al, Zn）49 and MgZn phases, and with increasing mass ratio of Zn to Al, the amount of the second phases in the alloys gradually increases and the distribution of the second phases changes from quasti-continuous net to uniform particles. In addition, the onset and peak temperatures of the second phase transformation for the experimental alloys with relatively low mass ratio of Zn to Al （〈2）, are higher than those of the alloys with high mass ratio of Zn to Al （〉2）, which results in different reactions during the second phase transformation and different types of the second phases.