热处理对Mg97.5 Gd1.9 Zn0.6 合金组织与力学性能的影响  

Effect of heat treatment on microstructure and mechanical properties of Mg97.5 Gd1.9 Zn0.6 alloy

作　　者：甄睿[1,2] 方信贤 皮锦红[1,2] 许恒源 吴震[1] ZHEN Rui;FANG Xin-xian;PI Jin-hong;XU Heng-yuan;WU Zhen(School of Materials Science and Engineering,Nanjing Institute of Technology,Nanjing 211167,China;Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology,Nanjing 211167,China)

机构地区：[1]南京工程学院材料科学与工程学院,南京211167 [2]江苏省先进结构材料与应用技术重点实验室,南京211167

出　　处：《材料工程》2020年第9期132-137,共6页Journal of Materials Engineering

基　　金：江苏省大学生创新创业训练计划项目(201911276034Y);南京工程学院科研基金(ZKJ201604)。

摘　　要：采用OM,SEM,TEM和电子万能试验机系统地研究了Mg 97.5 Gd 1.9 Zn 0.6合金在铸态、退火态、挤压态和挤压后直接时效(T5)的组织演化和力学性能。结果表明,合金的铸态组织由α-Mg、共晶形貌的(Mg,Zn)3Gd相和层片状的14H-LPSO相组成。在510℃均匀化退火过程中,发生了(Mg,Zn)3Gd转化成块状14H-LPSO的相变。根据生成相的形貌和发生反应的热力学条件得知其为包析转变,即(Mg,Zn)3Gd+α-Mg→14H-LPSO。挤压后直接时效(T5)处理过程中,发生了晶内14H-LPSO相和β′相的沉淀析出。在14H-LPSO强韧化与沉淀强化的共同作用下,合金的屈服强度和抗拉强度分别为216 MPa和361 MPa,伸长率也保持在较好的水平,为6.9%。A ternary alloy strengthened by the phase with long period stacking ordered(LPSO)structure with composition of Mg 97.5 Gd 1.9 Zn 0.6(atom fraction/%)was prepared by conventional permanent mold casting.The microstructure evolution and mechanical properties in as-cast,as-annealed,as-extruded and extruded-T5 alloy were systematically investigated by OM,SEM,TEM and electronic universal testing machine.The results show that the as-cast microstructure of the alloy consists of theα-Mg matrix,(Mg,Zn)3Gd eutectic and lamellar 14H-LPSO phase.Annealing at 510℃results in the transformation of(Mg,Zn)3Gd into the block-shaped 14H-LPSO phase.According to the distribution and morphology of the 14H-LPSO phase observed in the microstructure after annealing,the peritectoid transformation(Mg,Zn)3Gd+α-Mg→14H-LPSO possibly occurs during annealing.The lamellar 14H-LPSO andβ′p precipitates have also been observed in the alloy during extruded-T5 treatment.Under the combined action of 14H-LPSO toughening and precipitation strengthening,the aged sample shows the best tensile properties at room temperature:ultimate tensile strength of 361 MPa,yield strength of 216 MPa and elongation of 6.9%.

关 键 词：镁合金 长周期结构 热挤压 时效处理 相变 

分 类 号：TG146.22[一般工业技术—材料科学与工程]