表面纳米化对挤压时效态Mg-Gd-Y-Zr合金室温拉伸性能的影响  

Room-Temperature Tensile Properties of Extruded+Peak Aged Mg-Gd-Y-Zr Alloy Modified by Surface Nanocrystallization

作　　者：苑潇逸 宁江利 陶世洁 徐博 Yuan Xiaoyi;Ning Jiangli;Tao Shijie;Xu Bo(Department of Metal Materials and Processing Engineering,College of Metallurgy and Energy,North China University of Science and Technology,Tangshan 063210,China;Key Laboratory of Modern Metallurgy of the Ministry of Education,Tangshan 063210,China)

机构地区：[1]华北理工大学冶金与能源学院金属材料及加工工程系,河北唐山063210 [2]现代冶金技术教育部重点实验室,河北唐山063210

出　　处：《稀有金属》2022年第12期1546-1555,共10页Chinese Journal of Rare Metals

基　　金：国家国防科技工业局国防基础科研项目(JCKY2018407C008);华北理工大学杰出青年基金项目(JQ201702)资助

摘　　要：对热挤压+峰时效后的Mg-8.78Gd-2.82Y-0.47Zr(%,质量分数)合金进行表面机械研磨处理(SMAT),并分析其显微组织、力学性能和断裂方式等。结果表明,经SMAT后合金表面形成了梯度结构,可分为剧烈变形层、弱变形层和未受应变影响的基体层。SMAT使得表面亚结构数量增加,细晶粒呈现随机取向。SMAT后合金抗拉强度进一步上升,达449 MPa,延伸率为3.04%。强度的提升主要归因于表面变形层的晶粒细化和位错密度的增加。断裂形貌分析表明,SMAT后剧烈变形层的断口形貌以脆性特征为主,而靠近中心的弱变形层存在韧性和准解理断裂的混合特征。SMAT态合金较低的延伸率可能与剧烈变形层的脆性开裂有关。Magnesium alloys had wide application prospects because of their advantages of low density and high specific strength.However,the weak deformability and poor mechanical properties of magnesium alloys limited their further development of Mg alloys.The addition of rare elements such as Gd and Y could improve the mechanical properties of the alloys through solid solution strengthening and precipitation strengthening;and the addition of Zr could refine the grains of magnesium alloys and improve the tensile properties at room temperature.Mg-Gd-Y-Zr alloy showed high tensile strength and elongation attributed to the solid solution strengthening and precipitation strengthening.The alloy after hot extrusion usually exhibited a uniform and fine grain structure;the mechanical properties could be further improved with subsequent peak-aging treatment.Surface mechanical attrition treatment(SMAT)was carried out for alloys to further improve and the mechanical properties.The surfaces of alloy samples were impacted by steel balls at room temperature,the severely deformation of the surface could produce ultra-fine grains varied from nanometer to submicrometer.A gradient structure was obtained from the surface to the center of the sample after SMAT.Gradient structures showed synergistic strengthening effect,and usually had a good combination of strength and ductility superior to that of traditional homogeneous materials.SMAT was performed on the Mg-8.78Gd-2.82Y-0.47Zr(%,mass fraction)alloy after hot extrusion and peak aging(PA).Microstructures were analyzed by optical microscope(OM)and transmission electron microscope(TEM),and the mechanical properties were tested by nanoindentation tests and tensile tests at room temperature.The contribution of yield strength from each layer of the gradient structure was estimated according to different strengthening mechanisms.The fractography after tension was analyzed by scanning electron microscope(SEM).The results showed that a gradient structure was formed on the surface after SMAT,which ca

关 键 词：热挤压 MG-GD-Y-ZR合金 表面机械研磨处理(SMAT) 梯度结构 表面纳米化 断裂 

分 类 号：TG146.2[一般工业技术—材料科学与工程]