长周期堆垛有序结构强化Mg-Zn-Y合金的组织与性能

为研究长周期堆垛有序( LPSO)结构对Mg-Zn-Y变形镁合金组织与性能的影响,通过铸造和热挤压工艺制备了Mg97Zn1Y2和Mg94Zn2Y4合金.采用扫描电子显微镜、透射电子显微镜以及电子万能试验机等研究了2种合金在铸态、退火态以及挤压态下的显微组织和力学性能.研究结果表明,Mg97Zn1Y2和Mg94Zn2Y4合金的铸态组织均由α-Mg和18R型LPSO相构成,LP-SO相连接成网状分布在晶界.经500℃退火36 h后,Mg97 Zn1 Y2合金中部分块状LPSO相分解为细层片状,结构由18R转变为14H,但在Mg94Zn2Y4合金中未观察到LPSO相结构类型的转变.通过挤压变形,LPSO相沿挤压方向排列,合金强度得到大幅度提高,Mg97Zn1Y2和Mg94Zn2Y4合金的抗拉强度分别达到319和390 MPa.

Microstructure and properties of Mg-Zn-Y alloys with long period stacking ordered structure

In order to study the effects of long period stacking ordered(LPSO) structure on microstructure and mechanical properties of Mg-Zn-Y wrought alloys,Mg97Zn1Y2 and Mg94Zn2Y4 alloys were fabricated by casting and hot extrusion.Morphology and tensile properties of the alloys in the as-cast,annealed,and extruded stage were investigated by scanning electronic microscopy(SEM),transmission electronic microscopy(TEM) and electronic universal testing machine.The results show that the two as-cast alloys are composed of α-Mg and 18R-LPSO phase,and the LPSO phase forms a network at Mg grain boundaries.Annealed at 500℃ for 36h,a section of block-shaped 18R-LPSO phase is transformed into lamellar 14H-LPSO structure in Mg97Zn1Y2 alloy,but no remarkable changes are observed in Mg94Zn2Y4 alloy.After extrusion,LPSO phase is aligned along the direction of extruding and the strength of the alloys is promoted significantly.The tensile strength reaches 319 and 390 MPa for Mg97Zn1Y2 and Mg94Zn2Y4 alloys,respectively.