含长周期结构Mg-(2,3,4)Y-1Zn合金的显微组织和力学性能  

MICROSTRUCTURES AND MECHANICAL PROPERTIES OF Mg-(2,3,4)Y-1Zn ALLOYS WITH LONG PERIOD STACKING ORDERED STRUCTURE

作　　者：刘欢[1] 薛烽[1] 白晶[1] 周健[1] 孙扬善[1] 

机构地区：[1]东南大学材料科学与工程学院江苏省先进金属材料高技术研究重点实验室,南京211189

出　　处：《金属学报》2013年第2期236-242,共7页Acta Metallurgica Sinica

基　　金：江苏省自然科学基金资助项目BK2010392~~

摘　　要：制备并研究了Mg-(2,3,4)Y-1Zn(原子分数,%)三元合金在铸态、退火、挤压和固溶处理时的显微组织和力学性能.结果表明,随着Y/Zn原子比的升高,铸态合金的显微组织由WZ21和WZ31合金的两相组织(α-Mg+Mg_(12)YZn)转变为WZ41合金的三相组织(α-Mg+Mg_(12)YZn+Mg_(24)Y_5).其中Mg_(12)YZn相连接成网状,为18R-LPSO结构,Mg_(24)Y_5相分布于Mg_(12)YZn相之间.退火时,WZ21和WZ31合金中部分18R相溶解,基体中析出大量14H-LPSO层片.经过挤压,18R-LPSO相沿挤压方向呈带状排列,退火析出的14H层片整体平动,在α-Mg中仍相互平行.固溶处理后,18R相继续溶解,14H相析出并长大.此时,随Y/Zn原子比升高,合金中14-LPSO相体积分数增加.3种合金挤压态的性能优于相应的铸态、退火态和固溶处理态,随着Y含量的增加,合金强度不断升高,塑性下降,挤压态WZ41合金在室温时抗拉强度达到350 MPa以上.Recently, the Mg-Y-Zn alloy systems have received great attention due to their unique microstructures and excellent mechanical properties. Three kinds of ternary equilibrium Mg-Y-Zn phases have been reported in the systems： the W phase （Mg3Y2Zn3）, the I phase （Mg3YZu6） and the X phase （Mgl2YZn, long period stacking ordered （LPSO） structure）. To further study the evolutions of LPSO structures in Mg-Y-Zn alloys, three Mg-（2, 3, 4）Y-1Zn （atomic fraction, %） ternary alloys were prepared by casting and extrusion. Based on the OM, SEM and TEM observations, the microstructures of the as cast WZ21 and WZ31 alloys are mainly composed of a-Mg and Mg12YZn duplex microstructures, while that of the as cast WZ41 alloy consists of a-Mg, Mg12YZn and Mg24Y5 phases. The Mg12YZn phase which forms a network is a kind of 18R-LPSO structures and the Mg24Y5 phase is inclined to be located within 18R phases. During homogenization treatment, part of 18R phase dissolves and 14H lamellas are precipitated in the matrix of the WZ21 and WZ31 alloys. After extrusion, the 18R phases are aligned along the extrusion direction, whereas the 14H lamellas in the matrix are still parallel to each other. During solution treatment （T4）, the 18R structures continue todissolve and 14H lamellas further develop. With increase of the Y/Zn atomic ratio, the volume fraction of 14H-LPSO phase increases after T4 treatment. The mechanical properties for the extruded alloys are better than alloys in as-cast, as-annealed and T4-treated stages. With increasing Y content, the strength of the alloys increases, but the ductility decreases. Tensile strength of the extruded WZ41 alloy reaches 350 MPa at room temperature.

关 键 词：Mg-Y-Zn合金 长周期堆垛有序结构 退火 挤压 固溶处理 

分 类 号：TG146.22[一般工业技术—材料科学与工程]