混合稀土变质高硅铝活塞合金

采用镧铈钇型混合稀土对过共晶Al—24％Si活塞合金进行了变质处理，对其金相组织和力学性能进行了研究。结果表明：与单一稀土铈变质相比较，镧铈钇型混合稀土对该合金具有较好的变质效果，初晶硅的尺寸基本保持在20μm左右，且尖角大多钝化呈团球化状，共晶硅呈短杆状均匀分布；合金经过混合稀土变质后，晶界处产生复杂化合物组织起到了弥散强化作用，使其综合力学性能明显提高，尤其是高温强度的显著提高，已完全满足活塞合金在使用性能上对高温强度的要求。

High Silicon Aluminum Piston Alloy Modified with Mixed Rare Earths

Hypereutectie Al-24%Si alloy were modified with La-Ce-Yb mixed rare earths. The metallurgical microstrueture and mechanical property were studied using optical microscope. The results show that La-Ce-Yb mixed rare earths have better effect on modification than single Ce and the size of primary silicon is constantly 20μm or so. After modification of mixed rare earths, the comprehensive mechanical properties can be improved.