机械球磨结合粉末冶金制备AZ61超细晶镁合金的组织与性能  

Microstructure and Properties of AZ61 Ultra-Fine Grained Magnesium Alloy Prepared by Mechanical Milling and Powder Metallurgy Processing

作　　者：朱云鹏[1,2,3] 覃嘉宇 王金辉 马鸿斌[1,3] 金培鹏 李培杰[2] ZHU Yunpeng;QIN Jiayu;WANG Jinhui;MA Hongbin;JIN Peipeng;LI Peijie(Qinghai Provincial Key Laboratory of New Light Alloys,Qinghai University,Xining 810016,China;Department of Mechanical Engineering,Tsinghua University,Beijing 100084,China;Qinghai Provincial Engineering Research Center of High Performance Light Metal Alloys and Forming,Qinghai University,Xining 810016,China)

机构地区：[1]青海大学青海省新型轻合金重点实验室,西宁810016 [2]清华大学机械工程学院,北京100084 [3]青海大学青海省轻金属合金及深加工工程技术研究中心,西宁810016

出　　处：《金属学报》2023年第2期257-266,共10页Acta Metallurgica Sinica

基　　金：青海省科技厅基础研究项目No.2020-ZJ-707。

摘　　要：利用球磨与粉末冶金工艺相结合制备AZ61超细晶镁合金,分析了球磨对其晶粒尺寸、析出相、织构及室温拉伸性能的影响。结果表明,球磨及粉末冶金制备的AZ61镁合金与未经球磨处理制备的镁合金相比,其晶粒尺寸由0.91μm细化到0.68μm,且球磨处理促进了Mg_(17)Al_(12)的动态析出及细化,同时弱化了基面织构,其屈服强度、抗拉强度和伸长率分别为393.1 MPa、431.9 MPa和8.5%,综合力学性能优于其他工艺制备的AZ61镁合金。强化机制分析表明,细晶强化的贡献达到90%以上,沿晶界分布的Mg17Al12会降低Orowan强化效果,基面织构的弱化会降低屈服强度。未经球磨处理的镁合金的断裂机制是由镁粉表面的氧化引发粉体脱黏主导的;经球磨处理后其断裂机理为脱黏的粉体与周围未脱黏的组织变形不匹配及晶界上Mg_(17)Al_(12)数量增加导致的。The Mg-Al series alloys are well known for their low density,high specific strength,and superior damping capability.However,the application of Mg-Al series alloys is often limited by inadequate mechanical properties.To fulfill the growing demand for lightweight structural components,ultrafine grained magnesium alloys with superior mechanical properties have gained attention.Mechanical milling and powder metallurgy were used to produce the AZ61 ultra-fine grained magnesium alloy with super-high tensile characteristics.The effects of mechanical milling on the grain size,precipitates,texture,and tensile properties of AZ61 ultra-fine grained magnesium alloy were investigated.The grain size of the AZ61 alloy produced by mechanical milling and powder metallurgy was reduced from 0.91μm to 0.68μm when compared to that produced by non-mechanical milling.Mechanical milling accelerated the dynamic precipitation and refining of Mg_(17)Al_(12)while weakening the basal texture.The yield strength,tensile strength,and elongation of AZ61 ultra-fine grained magnesium alloy are 393.1 MPa,431.9 MPa,and 8.5%,respectively,which are superior to the AZ61 alloy produced by other processes.The theoretical grain refinement and Orowan strengthening mechanisms of AZ61 alloy were calculated,and it shows that the grain refinement strengthening contributes more than 90%of the yield strength.The Orowan strengthening was overestimated when Mg17Al12 was distributed at grain boundaries.The weakening of basal texture resulted in a reduction in yield strength.The fracture mechanism of the AZ61 alloy without mechanical milling is dominated by oxidation on the surface of the AZ61 powder,which initiates interparticle debonding.The fracture mechanism of the AZ61 alloy with mechanical milling is dominated by deformation mismatch between the deboned powders and the stronger bonded powders,and the increase in the amount ofMg_(17)Al_(12)along the grain boundary.

关 键 词：机械球磨 粉末冶金 AZ61超细晶镁合金 动态析出 强化机制 

分 类 号：TB31[一般工业技术—材料科学与工程]