电磁搅拌对等通道挤压前后Mg­Zn­Zr­Ca合金组织和性能的影响

摘要

Mg­2.0Zn­0.7Zr­0.5Ca alloy ingots with and without electromagnetic stirring were fabricated separately by controlling the application of the magnetic field in the casting process, and then were processed by the equal channel angular pressing (ECAP) technology. The effects of electromagnetic stirring on the microstructure and properties of the alloys before and after ECAP were studied. The results show that the microstructure and mechanical properties of the alloy with electromagnetic stirring are improved greatly compared with those of the alloy without electromagnetic stirring. Because electromagnetic stirring can refine the initial grain of the as­cast alloy, the grain refinement is obviously better than that of the as­cast alloy without electromagnetic stirring after 1 pass and 2 passes of ECAP. After 4 passes of ECAP, the grain size of the alloy with electromagnetic stirring becomes very small and uniform. At this time, the alloy has the best mechanical properties, and the microhardness, yield strength and elongation of the alloy reach 56.3HV, 276 MPa and 18.3%, respectively.%在合金熔炼过程中通过控制磁场的施加，分别制备无电磁搅拌和施加电磁搅拌的 Mg­2.0Zn­0.7Zr­0.5Ca镁合金铸锭。采用等通道挤压(ECAP)工艺分别对这两种状态的合金进行挤压加工，研究电磁搅拌对ECAP前后合金组织和性能的影响。结果表明：与无磁场状态相比，施加电磁搅拌后，合金的显微组织和力学性能均得到很大改善。因电磁搅拌能细化铸态合金的原始晶粒，经1道次和2道次ECAP后合金的晶粒细化程度明显优于无磁场状态的铸态合金的。4道次ECAP后施加电磁搅拌合金的晶粒非常细小、均匀，且性能最佳，其硬度、屈服强度和伸长率分别达到56.3 HV、276 MPa和18.3%。