挤压比对LZ92双相镁锂合金组织与力学性能的影响

Effect of Extrusion Ratio on Microstructure and Mechanical Properties of LZ92 Duplex Magnesium Lithium Alloy

采用真空感应熔炼方法制备LZ92(Mg-9Li-2Zn)双相镁锂合金,同时对合金进行热挤压试验,挤压比分别为10、20、30。采用光学显微镜(OM)、扫描电子显微镜(SEM)、X射线衍射(XRD)分析及硬度测试、拉伸测试等手段研究不同挤压比下LZ92双相镁锂合金的组织和性能。结果表明挤压态LZ92镁锂合金具有优异的力学性能;随着挤压比的增加,合金再结晶程度增加,晶粒细化程度更加明显,断口形貌中韧窝数量越多且分布均匀,抗拉强度逐渐增大至203.1 MPa,较铸态提高了76%。强度的提高主要是由于加工硬化和晶粒细化综合作用的结果。当挤压比从20增至30时,合金的延伸率却大幅下降,原因主要是加工硬化降低塑性变形能力的程度大于晶粒细化提高塑性变形能力的程度。

LZ92（Mg-9Li-2Zn） duplex magnesium lithium alloy was prepared by using vacuum induction melting method.It was carried out that separately controlled extrusion ratio of about 10,20,30 by hot extrusion deformation experiments.Microstructure and mechanical properties of LZ92 duplex magnesium lithium alloy were investigated by hardness test,tensile test,optical microscopy（OM）,scanning electron microscopy（SEM） and X-ray diffraction（XRD）.The results showed that LZ92 Mg-Li alloy had excellent mechanical properties after extrusion,with extrusion ratio increase,alloy recrystallization increase,more obvious grain refinement,more fracture morphology of toughening nest,and evenly distributed and tensile strength increasing to 203.1 MPa,compared with cast increased by 76 percent,It mainly due to the strength of the work hardening and grain refinement;when the extrusion ratio from 20 to 30,alloy＇s elongation dropped significantly,It mainly due to the hardening of the plastic deformation the ability to reduce the extent greater than the extent of grain refinement of plastic deformation increased.