稀土钇对Zn-25Al铸态组织及力学性能的影响

以Zn-25Al合金为基体材料,通过常规铸造方法制备了不同稀土含量的锌铝合金。采用金相显微镜、扫描电镜、拉伸试验机、硬度计等分析研究了稀土Y对试验合金显微组织和力学性能的影响。试验结果表明,添加稀土钇后,在锌铝合金中,其与Al、Zn等元素形成硬度高、热硬性好的复杂成分化合物且分散于晶界和枝晶中,细化了组织,有效地阻碍了高温时基体的变形和晶界移动。随着钇含量的增加,在室温、100℃和180℃3个温度下合金的抗拉强度和硬度基本上呈先升后降的趋势。当钇含量为0.6%时合金的综合性能最好,高温强度和硬度提高显著。180℃时的抗拉强度比不加Y时提高33.3%,硬度提高64.9%。当钇含量超过0.6%时力学性能下降。

Effects of Rare Earth Y on As-cast Microstructure and Mechanical Properties of Zn-25Al Alloy

The Zn-Al alloys which contain different content of rare earth element Y were produced by cast.,in which the Zn-25Al alloy was used as a matrix alloy.The effects of Y on the microstructure and mechanical properties of Zn-25Al alloys were investigated.Results showed that Y can react with Al,Zn and so on,to form some compounds with complex composition which have high hardness and good hot-hardness and can disperse in crystal interfaces or branch crystal interfaces so that the alloy has refined and deformation of matrix and movement of crystal interfaces at high temperature are tempered.With the Y content increasing,the mechanical properties rise at first but then follow the drop.The optimization of microstructure and performance was obtained with 0.6 wt % Y addition,especially the tensile strength and micro-hardness at high temperature.The alloy can be increased by 33.3% in tensile strength and by 64.9% in micro-hardness at 180℃.The mechanical properties descended when the Y content was higher than 0.6wt %.