中文摘要：

利用Al-La中间合金制备了AlSi10Cu0.2Mg0.2Mn-x La和Zn Al12Cu1（Mg）-x La铸造合金,考察了不同的La含量对合金组织和抗拉强度、伸长率、冲击强度等性能的影响.研究结果表明：微量稀土La可以细化合金的晶粒,改变Si相晶粒大小和形状.与未添加La的合金相比,含有微量稀土La的AlSi10Cu0.2Mg0.2Mn-x La合金和Zn Al12Cu1（Mg）-x La合金具有更优良的力学性能.当AlSi10Cu0.2Mg0.2Mn铸造合金中La添加量为0.15%（质量分数）时,铸造合金的伸长率增加2.7倍.含有0.1%（质量分数）La的Zn Al12Cu1（M g）-x La合金抗拉强度和伸长率相比于未添加稀土La的合金,分别增强1.3倍和3.2倍.含有0.3%（质量分数）La时Zn Al12Cu1（Mg）-x La的硬度增强1.8倍,但冲击强度是含有0.15%（质量分数）La时最高.综合考虑Zn Al12Cu1（Mg）-x La铸造合金的机械性能,稀土La的最优添加量为0.1%~0.2%（质量分数）.

英文摘要：

AlSi10Cu0.2Mg0.2Mn-xLa and ZnAl12Cu1（ Mg）-x La casting alloy were prepared by Al-La master alloy. The effect of La content on the microstructure,tensile strength,elongation and impact strength of these alloys were investigated. The results indicated that the crystalline grain of alloys could be refined by addition of La element and the size and shape of Si phase particle were also modified. Compared with the previous alloys,the mechanical properties of AlSi10Cu0. 2Mg0. 2Mn-x La alloy and ZnAl12Cu1（ Mg）-x La alloy containing traces of La were relatively improved. When 0. 15 wt% of La was added in AlSi10Cu0. 2Mg0. 2Mn casting alloy,the elongation could increase to 2. 7 times. The tensile strength and elongation of ZnAl12Cu1（ Mg）-x La containing 0. 1wt% of La was increased to 1. 3 and 3. 2 times,respectively. The hardness of ZnAl12Cu1（ Mg）-x La containing 0. 3wt% of La was increased to 1. 8 times while ZnAl12Cu1（ Mg）-x La containing 0. 15 wt% of La exhibited the maximum impact strength.Comprehensively considering the mechanical properties of ZnAl12Cu1（ Mg）-x La casting alloy,the optimal addition content of La was controlled in the range of 0. 1wt% ~ 0. 2wt%.