采用光学显微镜、扫描电镜、拉伸试验机等设备，研究了稀土元素镧对汽车轮毂用A356铝合金显微组织与力学性能的影响。结果表明：添加稀土元素镧后，A356铝合金中初生相α-Al得到显著细化，共晶硅形貌由粗大的针状或板条状变为细小的纤维状，共晶硅的平均面积和长径比分别从126 μm²和18.2减小至7.8 μm²和1.8；添加稀土元素镧后，铝合金中生成了AlSiLa金属间化合物；随着稀土元素镧含量的增加，铝合金的抗拉强度和伸长率均呈先升高后降低的趋势，当稀土元素镧质量分数为0.6%时，抗拉强度和伸长率均达到最大值，分别为215 MPa和5.4%。

The effect of rare earth element La on microstructure and mechanical properties of A356 aluminum alloys for automobile wheel hub was investigated by optical microscope, scanning electron microscope and tensile testing machine. The results show that the primary phase α-Al in the A356 aluminum alloy was refined after rare earth element La added. The morphology of eutectic Si changed from coarse acicular or lath-like into tiny fibrous. The mean area and aspect ratio of eutectic Si reduced from 126 μm² and 18.2 to 7.8 μm² and 1.8, respectively. AlSiLa intermetallic compound was obtained in the A356 aluminum alloy after rare earth element La added. The tensile strength and elongation increased first and then decreased with the increase of content of rare earth element La in the aluminum alloy. When the mass fraction of rare earth element La was 0.6%, the aluminum alloy had the maximum tensile strength and elongation which were 215 MPa, 5.4%, respectively.