挤压Mg-5Li-3Al-2Zn-2.1Ce合金的组织及压缩性能

Microstructure and Compressive Behavior of Mg-5Li-3Al-2Zn-2.1Ce Alloy

采用真空熔铸和挤压变形制备了一种Mg-5Li-3Al-2Zn-2.1Ce合金,通过OM、SEM、XRD以及EDS分析了合金的显微组织,在应变速率为1.67×10^(-4)、1×10^(-3)、5×10^(-3)和1×10^(-2) s^(-1)下对合金进行了室温压缩变形,分析了应变速率效应和变形机制。结果表明,Mg-5Li-3Al-2Zn-2.1Ce合金由α-Mg、Al_2Ce、Al_4Ce相组成,该合金最大压缩强度达到516.69MPa,最大应变为19%。在不同应变速率下合金表现为负的应变速率敏感性,在高应变区域,由于动态应变时效和孪晶的作用,发生塑性失稳现象。低应变速率压缩时的变形机制是再结晶协调的晶格滑移,高应变速率下变形机制是孪晶协调的晶格滑移。

Mg-5Li-3Al-2Zn-2.1Ce alloy was prepared by vacuum casting combined with extrusion deformation.The microstructure of the alloy was analyzed by OM（optical microscopy）,SEM（scanning electron microscopy）,XRD（X-ray diffraction）and EDS（energy dispersed spectrometer）,and the compressive behaviors were tested at 1.67×10^-4、1×10^-3、5×10^-3 and 1×10^-2 s^-1 at room temperature.The results show that Mg-5Li-3Al-2Zn-2.1Ce alloy is composed ofα-Mg,Al2Ce and Al4Ce phase.The maximum compression strength and the maximum strain of the alloy reach 516.69 MPa and 19%,respectively.At different strain rates,the strain rate sensitivity of the alloy is negative,and there exists a large number of twins in the alloy with high strain rate.The deformation mechanism at low strain rate compression is characterized by the lattice slip coordinated with recrystallization,and the deformation mechanism at high strain rate is characterized by the lattice slip coordinated with twins.