超细晶钛铝基合金的高温压缩性能研究  

High Temperature Compression Properties of Ultrafine TiAl-Based Alloy

作　　者：冀克明 曾婧 段振鑫 陈华 Ji Keming;Zeng Jing;Duan Zhenxin;Chen Hua(Key Laboratory of Advanced Structural Materials,Ministry of Education,School of Materials Science and Engineer-ing,Changchun University of Technology,Changchun 130012,China)

机构地区：[1]长春工业大学材料科学与工程学院先进结构材料教育部重点实验室,吉林长春130012

出　　处：《稀有金属》2022年第5期572-580,共9页Chinese Journal of Rare Metals

基　　金：国家自然科学基金项目(51371038)资助。

摘　　要：采用高能球磨及真空热压烧结的方法制备超细晶/纳米晶双相γ-TiAl基合金,将名义成分为Ti-45Al-7Nb(%,原子分数)的混合粉末经40 h高能球磨后,粉末达到纳米级。球磨后的混合粉末经真空热压烧结(烧结温度1200℃,压力30 MPa,保温保压1 h)。研究该合金在温度为1000,1050和1100℃,应变速率为1×10^(-4),1×10^(-3)和1×10^(-2)s^(-1)3个变形速率条件下的高温压缩组织、流变行为和本构关系。研究结果表明:经过高能球磨及真空热压烧结原位合成的组织为超细晶α_(2)-Ti_(3)Al及γ-TiAl双相等轴状合金组织,晶粒尺寸小于5μm。合金为热敏感型和应变速率敏感型合金,合金压缩流变应力随应变速率的降低和温度的升高而下降。高温热压缩时,合金组织由规整等轴状被压变形为长条形,形变主要发生在γ-TiAl相中,晶界和γ相晶内可见位错及孪晶,孪晶及位错为主要的形变机制。在1000,1050和1100℃,1×10^(-4),1×10^(-3)和1×10^(-2)s^(-1)条件下,Ti-45Al-7Nb等轴双相合金其热变形本构方程为:·ε=^(e36.62)[sinh(0.0066σ)]^(2.0349)exp(-506270/RT)。In this study,aγ-TiAl-based alloy of an ultrafine crystal/nanocrystalline double phase was prepared by high-energy ball milling and vacuum hot-pressing sintering.The powders with nominal composition of Ti-45Al-7Nb(%,atom fraction)were processed by high-energy ball milling for 40 h,and the powders reached nanometer lever.Then the alloy samples were prepared by vacuum hotpressed sintered with 1200℃of sintering temperature and 30 MPa pressure.Heat and pressure preservation were 1 h.The purity of Ti,Al and Nb powders was greater than 99.9%respectively.The average particle size of Ti powder was about 15μm,Al powder was about 20μm,and Nb powder was about 20μm.Scanning electron microscopy(SEM),transmission electron microscope(TEM)and X-ray diffractometer(XRD)patterns were used to study the change of the alloy powder particles.The compressive microstructure,rheological behavior and constitutive relationship of the alloy were investigated by high temperature compression tests at 1000,1050 and 1100℃and strain rates of 1×10^(-4),1×10^(-3) and 1×10^(-2)s^(-1).The research results showed that when the powder was milled for 15 h in the process of ball milling,the powders were deformed and refined.The reaction in this process belongs to the category of cold processing.The mixed powder particles were in irregular polygonal shapes,and the size of the mixed powder particle cluster was 3~14μm.When the milled time was extended to 25 h,the temperature of the system rose due to the continuous energy generation during the ball milling process,and a small amount of agglomeration began to occur.The particle size of the agglomeration of powders was about 2μm.When the ball milling time was 40 h,the refinement of the mixed powder particles became more obvious,and the agglomeration of the powder became more serious.At this point,the observed powder particles were less than 0.5μm,and the original micron powder particles became smaller and thinner to the nanometer level.The diffraction peaks of Ti,Al and Nb were observed in the m

关 键 词：钛铝基合金 热压缩 流变应力 本构方程 

分 类 号：TG146.23[一般工业技术—材料科学与工程]