铸态Mg-7Gd-5Y-1.2Nd-Zr镁合金热变形行为研究  

Hot Deformation Behavior of As-cast Mg-7Gd-5Y-1.2Nd-Zr Magnesium Alloy

作　　者：马鸣龙[1] 张奎[1] 李兴刚[1] 李永军[1] 张康[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

出　　处：《特种铸造及有色合金》2009年第3期197-200,共4页Special Casting & Nonferrous Alloys

基　　金：国家重点基础研究发展计划(973计划)资助项目(2007CB613705);国家"十一五"支撑计划项目(2006BAE04B01)

摘　　要：针对Mg-7Gd-5Y-1.2Nd-Zr镁合金,研究了其铸态显微组织以及在Gleeble-1500D热模拟机上单向压缩的力学行为,其应变速率为2×10-3～1s-1,变形温度为573～723K,压下量为60%。铸态Mg-7Gd-5Y-1.2Nd-Zr合金组织由α-Mg基体和网状的共晶构成;变形温度和应变速率对合金的峰值应力有明显的影响,在相同变形温度条件下,峰值应力随应变速率的增加而升高;在相同的应变速率条件下,峰值应力随变形温度的升高而降低;高温条件下的共晶组织的软化也是合金变形抗力下降的重要原因;应变速率为10-1s-1时,合金不连续动态再结晶最为明显,合金易于失效;同时计算出了平均热变形激活能Q为243.5kJ/mol和应力指数n为4.1972,分析得出变形激活能直接受到变形温度的影响,间接受到应变速率的影响。As-cast microstructure of Mg-7Gd-5Y-1.2Nd-Zr magnesium alloy was observed,and the mechanical behavior of the alloy during hot deformation process was examined on the Gleeble-1500D hot simulator with reduction of 60% and strain rates of 0.002,0.01,0.1,1 s-1 at 573～723K.As-cast microstructure of the alloy is composed of α-Mg phase and net-like eutectic phase.At a given temperature,the peak stress is increased with increasing in strain rate;while with a given strain rate,it is decreased with increasing in deformation temperature.Softening of eutectic phase in microstructure of the alloy plays an important roles in decreasing in peaking stress at high temperatures.Discontinuous recrystallization in the alloy is more distinct at strain rate of 0.1 s-1,resulting in the failure of alloy.Average deformation activation energy and stress exponent are 243.5kJ/mol and 4.1972,respectively.The deformation activation energy is related directly to deformation temperature and related indirectly to strain rate.

关 键 词：稀土镁合金 热变形 微观组织 流变应力 变形激活能 

分 类 号：TG146.22[一般工业技术—材料科学与工程] TG113[金属学及工艺—金属材料]