铸造Mg-RE合金的显微结构及其蠕变行为

Microstructure and creep behavior of a cast Mg-RE alloy

研究了铸造Mg-RE合金的高温蠕变特性,通过SEM和TEM观察,讨论与分析了该合金的蠕变机制.结果表明:在473K、应力低于100MPa条件下,该合金具有良好的蠕变抗力,其稳态蠕变速率低于2.66×10^(-6)s^(-1);富含Ce、La、Nd等稀土元素的共晶β相和蠕变期间动态沉淀产生的晶界强化及沉淀强化是该合金的主要强化机制,而孪晶切变和共晶β相开裂致使其高温蠕变抗力显著降低。

The compress creep tests of a cast Mg-RE alloy were carried out at constant stress on Mayes fatigue machine in air, and the creep behavior of the alloy was investigated at different temperatures. Observations by SEM and TEM show that the creep resistance of the alloy is relatively high at 473 K under stress &le100 MPa and the steady creep rate is lower than 2.66×10-6s-1. The eutectic β phases comprised Ce, La, Nd etc elements and dynamic precipitations during creep are proposed to be the principal strengthening mechanism of the alloy, whereas the main reason for the decrease of the creep resistance is the twins shear deformation and cracking of the eutectic β phases.