Mg-9.0Y-3.0MM-0.6Zr合金均匀化热处理研究  

Homogenization Heat Treatment of Mg-9.0Y-3.0MM-0.6Zr Alloy

作　　者：何兰强[1] 马鸣龙[1] 李兴刚[1] 李永军[1] 张奎[1] 

机构地区：[1]北京有色金属研究总院有色金属材料制备加工国家重点实验室,北京100088

出　　处：《稀有金属》2011年第2期164-169,共6页Chinese Journal of Rare Metals

基　　金：国家重点基础研究发展计划资助项目(2007CB613704;2007CB613705)

摘　　要：通过OM,SEM及拉伸性能测试,研究了Mg-9.0Y-3.0MM-0.6Zr铸态合金均匀化温度与时间对显微组织的影响,确定该合金合适的均匀化工艺。结果表明:Mg-9.0Y-3.0MM-0.6Zr铸态合金显微组织主要由α-Mg基体相、Mg12(MM)相以及Mg24Y5相组成,晶粒度约为45μm;505,520℃均匀化温度较低,Mg-Y相分解不够完全;经535℃保温18 h均匀化处理后,仅在晶界处残留Mg12(MM)相,延长时间晶粒尺寸没有变化,可见Mg12(MM)相可有效抑制合金晶粒长大;535℃×18 h均匀化处理后合金的力学性能较铸态合金没有明显改变,均匀化态的合金经挤压后,力学性能大幅度提升,σ0.2,σb,δ分别为245,305 MPa和12.5%。均匀化处理后合金断口形貌与铸态合金相似,仅在局部存在少量的韧窝,室温下断裂方式为脆性断裂;挤压后的合金断口形貌呈典型的韧性断裂特征。The impact of homogenization time and temperature on microstructures and properties of the as-cast and homogenized Mg-9.0Y-3.0MM-0.6Zr alloy were investigated by optical microscopy,scanning electron microscopy and tensile test.The homogenization parameters were determined.The results indicated that the Mg-9.0Y-3.0MM-0.6Zr as-cast microstructures consisted of phases of α-Mg,Mg12（MM） and Mg24Y5 with an average grain size of 45 μm.505 and 520 ℃ were too low to make Mg-Y phase dissolve completely.After homogenizing at 535 ℃ for 18 h,there were only Mg12（MM） phases remained and the grains did not grow up as prolonging the homogenization time,indicating that Mg12（MM） phase could efficaciously restrain grain coarsening.The mechanical properties were not significantly changed after homogenization at 535 ℃ for 18 h,compared with the as-cast alloy.The mechanical properties of the homogenization alloy after extrusion were improved obviously,with σ0.2,σb,δ being 245,305 MPa and 12.5% respectively.The fracture morphology of the as-cast alloy was similar to the homogenized alloy at room temperature.There were a few dimples on local part of the fracture surface,indicating that brittle fracture was the main fracture mechanism.However,the fracture morphology of extruded alloy presented typical ductile fracture characteristics.

关 键 词：稀土镁合金 均匀化处理 显微组织 力学性能 

分 类 号：O614.22[理学—无机化学]