将铸态Mg-5Sn-1.5Al-1Zn-0.8Si镁合金进行往复挤镦变形,采用OM、SEM和EDS等分析合金组织,重点研究了往复挤镦对该合金显微组织、力学性能及断口形貌的影响.结果表明:多道次往复挤镦可显著细化实验合金的显微组织,经过挤镦变形后,平均晶粒尺寸由铸态的50 μm细化至3μm左右,组织中的第二相被破碎且呈现弥散分布.往复挤镦可大幅度提高实验合金的力学性能,其硬度、抗拉强度和延伸率分别比铸态试样提高了47％、155％和110％,挤镦变形合金的拉伸断口出现大量韧窝,断裂方式为典型的韧性断裂.%As-cast Mg-5Sn-l. 5Al-lZn-0. 8Si magnesium alloy was processed by reciprocating extrusion (RE). Microstructure of the alloy was studied with OM, SEM and EDS. Effects of reciprocating extrusion on microstruc-ture, mechanical property and fracture morphology were particularly discussed. The results indicate that multi-pass reciprocating extrusion has the strong refinement on microstructure, the average grain size of as-cast decreases from 50 μm to 3 μm after reciprocating extrusion, second-phase is broken and dispersive distributioa Reciprocating extrusion can greatly improve mechanical property of the alloy. Compared with as-cast alloy, the hardness, tensile strength and elongation of reciprocating extrusion alloy are increased by 47%, 155% and 110% respectively. After reciprocating extrusion, the tensile fracture of the alloy appears massive dimples, and fracture mode is typical ductile fracture as well.
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