激光直接熔化沉积TA15合金高温原位拉伸过程中的组织演变行为  

Microstructure Evolution Behavior of Laser Melting Deposited TA15 Alloy During High Temperature In-situ Tension

作　　者：柴如霞 吕俊霞(指导)[1] 谢强[1] RIZWAN Muhammad 张跃飞[1] 张泽[2] CHAI Ruxia;Lü Junxia;XIE Qiang;RIZWAN Muhammad;ZHANG Yuefei;ZHANG Ze(Faculty of Materials and Manufacturing,Beijing University of Technology,Beijing 100124,China;School of Materials Science and Engineering,Zhejiang University,Hangzhou 310027,China)

机构地区：[1]北京工业大学材料与制造学部,北京100124 [2]浙江大学材料科学与工程学院,杭州310027

出　　处：《机械工程材料》2021年第11期84-90,共7页Materials For Mechanical Engineering

基　　金：国家自然科学基金基础科学中心项目(51988101);北京市自然科学基金重点项目(KZ202110005006)。

摘　　要：采用自主开发的原位高温扫描电镜-电子背散射衍射(SEM-EBSD)微拉伸系统,对激光直接熔化沉积(LMD)TA15合金进行300℃原位拉伸试验,研究了原位拉伸变形过程中的合金微观结构演变及断裂行为。结果表明:在高温拉伸变形时滑移是LMD TA15合金发生塑性变形的主要机制,裂纹扩展路径与滑移带扩展路径一致,均切过α板条簇进行扩展。合金的断裂方式为脆性-韧性混合断裂,其中β晶界的存在是造成合金局部区域发生脆性断裂的根本原因。变形前期,晶粒发生旋转,合金发生均匀塑性变形;随着应变量的增加,通过位错运动使局部晶粒内部产生大量低角度晶界,占比从拉伸前的4.9%增加到应变为12%时的33.7%,合金发生非均匀变形。In-situ tensile tests at 300℃of laser melting deposited(LMD)TA15 alloy were carried out by in-situ high temperature scanning electron microscopy-electron backscattering diffraction(SEM-EBSD)mircotensile system.The microstructure evolution and fracture mechanism of the alloy during in-situ tension were studied.The results show that slip was the main plastic deformation mechanism in the LMD TA15 alloy during tension at high temperature.The crack propagation path was consistent with the slip band propagation path,and both propagated by cutting through theαstrip cluster.The fracture of the alloy presented the brittle-ductile mixed fracture mode,and the existence ofβgrain boundaries was the root cause of local brittle fracture.In the early stage of deformation,grains rotated,and uniform plastic deformation of the alloy occurred.With increasing strain,there were a lot of low-angle grain boundaries in local grain by dislocation,and the fraction of low-angle grain boundaries increased from 4.9%before tension to 33.7%at the strain of 12%;inhomogeneous deformation of the alloy occurred.

关 键 词：激光直接熔化沉积 TA15合金 高温原位拉伸 EBSD 滑移 

分 类 号：TG146[一般工业技术—材料科学与工程]