铸态与挤压态AM50-4%(Zn,Y)合金组织及力学性能

Microstructure and Mechanical Properties of As-cast and Extruded AM50-4%(Zn,Y)Alloys

在AM50合金中加入质量分数为4%的(Zn,Y)(Zn、Y原子比为6),通过OM、XRD、SEM/EDS、EBSD和拉伸试验研究了铸态AM50、铸态及挤压态AM50-4%(Zn,Y)合金的组织和力学性能。结果表明:将Zn、Y加入AM50合金后,组织主要由α-Mg、β-Mg 17(Al,Zn)12和Φ-Mg 21(Zn,Al)17相以及少量Al 6YMn 6和Al 2Y相组成。添加Zn、Y元素使AM50合金组织细化,β相的数量减少且形貌改善,铸态力学性能提高。在370℃对AM50-4%(Zn,Y)合金进行热挤压变形后,固溶到基体中的β-Mg 17(Al,Zn)12相沿晶界析出,而Φ相并未析出。同时,少量的Al 6YMn 6和Al 2Y相仍弥散分布于合金基体中。此外,EBSD分析表明,挤压后晶粒细化至7.32μm,且呈现出典型的挤压织构。由于晶粒细化、沉淀强化以及挤压合金的典型织构,挤压态AM50-4%(Zn,Y)合金的力学性能得到进一步提高,其抗拉强度、屈服强度和伸长率分别达到303 MPa、193 MPa和13%。

The microstructures and mechanical properties of as-cast AM50,as-cast and extruded AM50-4%(Zn,Y)alloys(the atomic ratio of Zn and Y is 6)were studied by OM,XRD,SEM/EDS,EBSD and tensile tests.The results show that the microstructure of alloy is mainly composed ofα-Mg,β-Mg 17(Al,Zn)12 andΦ-Mg 21(Zn,Al)17 phases and a small amount of Al 6YMn 6 and Al 2Y phases when Zn,Y elements are added to AM50 alloy.The addition of Zn,Y element refined the microstructure of AM50 alloy,improved the morphology ofβphase,and improved the comprehensive mechanical properties of the alloy.After hot extrusion deformation of AM50-4%(Zn,Y)alloy at 370℃,theβ-Mg 17(Al,Zn)12 phase dissolved in the matrix precipitates again along the grain boundary,but theΦphase did not precipitate.At the same time,a small amount of Al 6YMn 6 and Al 2Y phases were still dispersed in the alloy matrix.In addition,EBSD analysis shows that the grain size is refined to 7.32μm after hot extrusion,and show a typical extrusion texture.Due to grain refinement,precipitation strengthening and typical texture of extruded alloy,the mechanical properties of extruded AM50-4%(Zn,Y)alloy were further improved,and its tensile strength,yield strength and elongation can reach to 303 MPa,193 MPa and 13%,respectively.