稀土La对ZL101A合金组织及性能的影响

在ZL101A合金中加入不同量La，研究了其微观／宏观组织和热处理后的性能。实验结果表明。在金属型铸造条件下，加入质量分数为0．6％左右的La对ZL101A合金具有最好的变质效果，共晶硅全部变为细小点状。稀土La的加入可将合金晶粒尺寸由未变质时的3mm细化到1mm。共晶硅变质以及晶粒细化主要是由于加入的La富集在共晶硅前沿，阻碍了共晶硅长大。合金抗拉强度和伸长率随着La的增加而提高，但La超过一定量后合金抗拉强度和伸长率均会有不同程度的降低。

Effect of La on Structure and Properties of ZL101A Alloy

The micro/macro-structure and properties of the ZL101A alloy added different La amount alter heat treatment were studied. The results show that a significant modifying effect on ZL101Acan be achieved in metal mouldcasting by adding 0.6% La the eutectic Si in the modified alloy becomes finer spot-shaped morphology. The grain is refined remarkably after adding La and the average grain size is decreased from 3 mm to 1 mm. The modification of eutectic silicon and the refinement of grain are mainly attribute to the enrichment of La at the front edge of eutectic,which counteracts the eutectic Si growing up. With the increase of La amount, the tensile strength and elongation increase markedly. But excessive La has bad effect on tensile strength and elongation.