超声处理对含稀土的AZ91镁合金性能及组织的影响  

Properties and Microstructure of Rare Earth AZ91 Magnesium Alloy with Ultrasonic Treatment

作　　者：李尧[1] 杨俊杰[1] 刘智超[1] 

机构地区：[1]江汉大学机电与建筑工程学院,武汉湖北430056

出　　处：《稀有金属》2016年第11期1107-1111,共5页Chinese Journal of Rare Metals

基　　金：湖北省自然科学基金重点项目(2008CDA028);武汉市科技计划项目(201250499145-16)资助

摘　　要：在AZ91镁合金熔炼过程中加入混合稀土Y,Gd并辅以超声熔体处理工艺制备合金,利用万能试验机、光学显微镜(OM)和透射电镜(TEM),探讨了添加混合稀土和超声波处理对AZ91镁合金微观组织和力学性能的影响,分析了其作用机制。实验结果表明,添加混合稀土Y,Gd后,未经超声处理的合金,稀土化合物存在于合金晶内和晶界上,α-Mg基体组织得到细化,晶界上的β相减少,合金的抗拉强度σb和延伸率δ可分别达到261 MPa和4.5%。同时,施加超声处理能进一步细化合金组织,α-Mg基体晶粒更加等轴细小,抑制β相在晶界处的连续网状分布。稀土相趋于弥散均匀分布,促进了稀土元素的细晶强化作用,这样使合金抗拉强度提高到270 MPa,延伸率达到7.2%。当混合稀土添加总量超过一定范围后,会形成粗大化合物并割裂基体,这时超声处理对合金组织的改善作用有限,合金力学性能呈现下降趋势。Mixed rare earth （RE） Y and Gd were added into AZ91 magnesium alloy during the melting process aided with ultrasonic treatment to produce RE-AZ91 alloy. By means of tensile testing machine, optical microscopy （OM） and transmission electronic microscopy （ TEM）, the effects of RE and ultrasonic treatment on properties and microstructure were discussed. The experimental results showed that, in the RE-AZ91, abundant RE compound could be observed inside the crystalline and along the crystalline boundary, cL- Mg matrix was refined, 13-phase decreased, and the tensile strength σb and the elongation δ could reach 261 MPa and 4.5%, respectively. After experiencing ultrasonic treatment, microstructure of RE-AZ91 could be refined further and α-Mg matrix crystalline size grew smaller, the net morphology of β-phase distributed on the crystalline boundary was limited. In addition, RE phases tended to dis- tribute homogeneously so as to improve the fine-crystal strengthening effect. As a result, the tensile strength σb and the elongation δ increased to 270 MPa and 7.2% , respectively. However, if the amount of mixed RE exceeded a certain level, the coarsened RE compound could be formed and weakened the strength of the matrix, resulting a limited effect of uhrasonic treatment and a decreasing me- chanical properties.

关 键 词：AZ91镁合金 稀土元素 超声波处理 力学性能 

分 类 号：TG146.45[一般工业技术—材料科学与工程] TG146.22[金属学及工艺—金属材料]