Nd对ZK60镁合金组织和阻尼性能的影响

Effects of Nd on Microstructure and Damping Properties of ZK60 Magnesium Alloy

采用MDA 8Q00型动态机械分析仪测试了试验合金的阻尼性能,研究了稀土元素Nd对ZK60镁合金阻尼性能的影响,并对合金在铸态、固溶态和挤压态下的阻尼性能进行了对比分析。结果表明,Nd的加入,改善了合金结构,细化了晶粒尺寸。加Nd后,铸态ZK60合金由原来的基体相α-Mg和MgZn两相组成变成了由基体相α-Mg+MgZn+MgNdZn三相组成,晶粒大小由100μm细化为35μm左右。部分Nd原子的固溶,缩短了弱钉扎点间的长度LC,降低了合金的应变无关阻尼。但MgNdZn相与α-Mg基体之间的相互作用,产生大量的可动位错,提高了合金的应变相关阻尼。在中等应变振幅范围内(1×10^(-4)≤ε≤4×10^(-4)),加Nd的ZK60镁合金在铸态、固溶态和挤压态下的阻尼性能均好于不加Nd的合金。

Damping capacity of the test alloys was tested by MDA 8Q00 dynamic mechanical analyzer.The effects of rare earth element Nd on the damping capacities and microstructure of ZK60 magnesium alloys were analyzed,and the damping properties of the alloys at as-cast,as-solution and as-extruded were compared.The results show that the grains in the alloy at as-cast state are refined from 100μm to approximately 35μm and the microstructure of the alloy is changed from two phases ofα-Mg＋MgZn to three phases ofα-Mg＋MgZn＋MgNdZn owing to the addition of rare earth element Nd.The lengths in the weak pinning points are shortened and the strain independent damping capacities of the alloy are reduced because of solid solution of Nd atoms.However,the strain dependent damping values of the alloy with Nd are improved by a large number of movable dislocations produced by interaction between MgNdZn andα-Mg matrix.In moderate strain amplitude range（1×10^-4≤ε≤4×10^-4）,damping properties of ZK60 magnesium alloys at as-cast,as-solution and as-extruded,containing rare earth element Nd,are higher than that of alloys without Nd,respectively.