超声振动压缩AZ91镁合金的组织演变与变形机理研究  

Microstructure Evolution and Deformation Mechanism of AZ91 Magnesium Alloy during Ultrasonic Vibration Compression

作　　者：徐紫玥 刘欢[1,2] 雷浩 江静华[1] 马将[3] XU Ziyue;LIU Huan;LEI Hao;JIANG Jinghua;MA Jiang(College of Materials Science and Engineering,Hohai University,Jiangsu Changzhou 213200,China;Baowu Magnesium Technology CO.,Ltd.,Nanjing 211200,China;College of Mechatronics and Control Engineering,Shenzhen University,Guangdong Shenzhen 518060,China)

机构地区：[1]河海大学材料科学与工程学院,江苏常州213200 [2]宝武镁业科技股份有限公司,南京211200 [3]深圳大学机电与控制工程学院,广东深圳518060

出　　处：《精密成形工程》2024年第11期19-27,共9页Journal of Netshape Forming Engineering

基　　金：国家自然科学基金(52271101);南京市重大科技专项(202309015)。

摘　　要：目的探究室温超声振动压缩(UVC)作用下镁合金的成形和应用潜力,研究AZ91固溶镁合金经UVC加工后的微观组织和力学性能演变规律,并探究其变形机理。方法在室温、频率20kHz和气压100kPa条件下对固溶态AZ91镁合金进行不同时间(0~1 s)的UVC加工,利用光学显微镜、XRD、SEM、TEM和显微硬度等手段研究UVC后合金的微观组织、力学性能和变形机理。结果在室温UVC加工过程中,AZ91合金的圆周伸长率和真应变逐渐增加。加载时间为1s时,合金的圆周伸长率和真应变分别达到80%和1.2,显著高于传统压缩。UVC过程中所需的最大应力仅为37.18MPa,温度最高达243℃。随着UVC时间的延长,合金中出现大量变形带,且变形带内析出亚微米级的Mg_(17)Al_(12)第二相。合金中的位错密度显著提升,逐步发生动态回复和动态再结晶细化晶粒。UVC后,合金的显微硬度由固溶合金的70.6HV显著提升至102.1HV。UVC作用下能够实现固溶镁合金高应变速率、大应变量变形的主要原因是合金中变形带和孪晶的快速增殖。此外,变形带内第二相的迅速析出、动态回复和再结晶也对合金的变形起到促进作用。结论固溶AZ91镁合金在超声振动压缩作用下展现了良好的变形能力和成形潜力,通过改进超声工艺有望在室温下实现镁合金的高应变速率大应变量超塑性成形。The work aims to explore the forming and application potential of magnesium alloy under ultrasonic vibration compression(UVC)at room temperature by investigating the evolution of microstructure and mechanical properties of solid so-lution-treated AZ91 magnesium alloy during UVC processing,as well as the deformation mechanism.The solid solution-treated AZ91 alloy was processed by UVC at room temperature,20 kHz and 100 kPa for different time(0-1 s).The microstructure,mechanical properties and deformation mechanism of the alloy during UVC were studied by optical microscopy,XRD,SEM,TEM and microhardness tests.The results showed that the circumference elongation and true strain of AZ91 alloy increased gradually during UVC.When the loading time was 1 s,the circumferential elongation and true strain of the alloy reached 80%and 1.2,respectively,which were significantly higher than those after conventional compression.The maximum stress required in the UVC process was only 37.18 MPa and the highest temperature was to 243.With the extension of the UVC time,a large℃number of deformation zones appeared in the alloy,and the Mg_(17)Al_(12)second phases of submicron level were precipitated within the deformation zones.The dislocation density in the alloy increased significantly,and dynamic recovery and recrystallization gradually occurred to refine the grains.After UVC,the microhardness of the alloy significantly increased from 70.6HV to 102.1HV.The re-alization of high strain rate and large strain deformation of magnesium alloy under UVC was mainly ascribed from the rapid gen-eration of deformation bands and twins in the alloy.In addition,the rapid precipitation of Mg_(17)Al_(12)phase,dynamic recovery and re-crystallization ofα-Mg grains in the deformation zone also promoted the deformation of the alloy.In conclusion,the solu-tion-treated AZ91 alloy exhibits good deformation ability and forming potential under UVC,which suggests that high-strain-rate and large-strain superplastic forming of Mg alloys may be achieved at room

关 键 词：AZ91镁合金 超声振动压缩(UVC) 显微组织 力学性能 变形机理 

分 类 号：TG306[金属学及工艺—金属压力加工]