Mg-6Al-1Nd-1.5Gd合金的高温蠕变机制

采用高温蠕变装置,研究了Mg-6Al-1Nd-1.5Gd合金在150、175、200℃以及50、70、90 MPa条件下的高温压缩蠕变行为,分析合金在高温蠕变过程中的蠕变机制。结果表明,Mg-6Al-1Nd-1.5Gd合金的平均应力指数及蠕变激活能分别为4.64和73.87kJ/mol,其主要蠕变机制是由位错攀移和晶界扩散共同作用,合金的蠕变本构方程为:ε=1.877×10-8σ4.641exp-73 865/(RT)];合金在高温蠕变过程中,微观组织中的位错密度逐渐增大,出现位错缠结及位错堆积,合金蠕变后的晶粒变得粗大,金属间化合物Al3Nd和Al3Gd在晶界上出现偏聚。

High Temperature Creep Mechanism of Mg-6Al-1Nd-1.5Gd Alloy

The high temperature creep behavior of Mg-6Al-1Nd-1.5Gd alloy under 150,175,200 ℃ and 50,70,90 MPa conditions was investigated by using a high temperature creep device,and the alloy was analyzed for high temperature creep mechanism in the process.The results show that the average stress index and creep activation energy of Mg-6Al-1Nd-1.5Gd alloy reach 4.64 and 73.87 kJ/mol,respectively.The main creep mechanism is characterized by the dislocation creep and grain boundary diffusion.The creep constitutive equation is ε=1.877×10-8σ4.641 exp-73 865/(RT)].During the high temperature creep of the alloy,the dislocation density in the alloy’s microstructure is increased gradually,and dislocation entanglement and dislocation accumulation appear.In addition,the grains of the alloy are coarsened after creep,and the intermetallic compounds Al3Nd and Al3Gd are segregated at the grain boundaries.