含NiAl涂层的TC4钛合金板材的拉伸失效机理  

Tensile failure mechanism on TC4 titanium alloy sheet containing NiAl coating

作　　者：郑晖[1] 孙凌崴 韩颖杰[2] 付和国 谢洪志[2] 张帅[2] 赵天章[1] Zheng Hui;Sun Lingwei;Han Yingjie;Fu Heguo;Xie Hongzhi;Zhang Shuai;Zhao Tianzhang(School of Aeronautics and Astronautics,Shenyang Aerospace University,Shenyang 110136,China;Shenyang Aircraft Corporation,Shenyang 110034,China)

机构地区：[1]沈阳航空航天大学航空宇航学院,辽宁沈阳110136 [2]沈阳飞机工业(集团)有限公司,辽宁沈阳110034

出　　处：《锻压技术》2023年第10期46-52,共7页Forging & Stamping Technology

基　　金：国家自然科学基金青年科学基金项目(51605310);辽宁省教育厅项目(LJKZ0180);沈阳市中青年科技创新人才支持计划(RC210422)。

摘　　要：利用等离子喷涂技术在TC4钛合金零件表面制备涂层是常见的增强钛合金性能的方法,但变形时涂层的失效机理尚不明确。通过室温拉伸试验测试了含NiAl涂层的TC4钛合金板材的力学性能,深入分析了各阶段力学行为的特点。通过金相显微镜观察了涂层中的裂纹,明确了涂层的失效原因,并建立了单向拉伸涂层的失效模型。结果表明:涂层的失效是由开裂和脱粘引起的,开裂是在涂层的厚度方向贯穿涂层的裂纹,脱粘是基体与涂层的机械结合失效导致的分离。开裂和脱粘是涂层失效过程的两个阶段:开裂发生在拉伸前期的弹性阶段,在应力的作用下在涂层中的缺陷处或涂层表面开裂;而脱粘主要发生在拉伸后期的塑性阶段,涂层与基体的结合失效导致涂层脱落。涂层的周期性开裂导致弹性阶段的应力-应变曲线呈现周期性的台阶形状,塑性阶段涂层的脱粘与开裂相遇导致部分涂层残留在基体上。Using plasma spraying technology to prepare coatings on the surface of TC4 titanium alloy parts is a common method to enhance the properties of titanium alloy,but the mechanism of coating failure during deformation is not clear.Therefore,the mechanical properties of NiAl-coated TC4 plate were tested through tensile tests at room temperature,and the characteristics of the mechanical behavior at each stage were analyzed in depth.Then,the cracks in the coating were observed by metallography microscope,the cause of coating failure was clarified,and a uniaxial tensile coating failure model was established.The results show that the failure of coating is caused by cracking and debonding.The cracking is the crack that runs through the thickness of coating,and the debonding is the separation caused by the mechanical bonding failure between matrix and coating.Cracking and debonding are two stages of the coating failure process.Cracking oc-curs in the elastic stage during the early stage of stretching,which occurs at defects in the coating or on the surface of coating under the action of stress,while debonding mainly occurs in the plastic stage during the later stage of stretching,the bonding failure between coating and substrate leads to the coating to fall off.The periodic cracking of coating causes the stress-strain curve in the elastic stage to show a periodic step shape,while the debonding and cracking of the coating in the plastic stage lead to part of the coating remaining on matrix.

关 键 词：NIAL涂层 TC4钛合金 失效模型 开裂 脱粘 

分 类 号：TG174.4[金属学及工艺—金属表面处理]