热循环对NiTi合金焊接接头相变的影响  

Effect of thermal cycling on the transformation of laser-welded NiTi alloy

作　　者：阎小军[1] 杨大智[1] 刘晓鹏[1] 

机构地区：[1]大连理工大学材料工程系,辽宁大连116024

出　　处：《材料科学与工艺》2007年第4期453-455,共3页Materials Science and Technology

基　　金：国家自然科学基金资助项目(50471066)

摘　　要：为了研究热循环对NiTi合金激光焊接接头相变行为的影响,用激光点焊了Φ0.5 mmTi-50.6%Ni合金细丝,利用金相显微镜观察了母材和接头的显微组织,通过示差热分析仪研究了热循环对点焊接头相变行为的影响.结果表明,NiTi合金激光点焊接头,熔化区为树枝晶,热影响区由粗大等轴晶和细小等轴晶组成.热循环可改变接头的相变行为,使马氏体相变由B2→B19′转变为B2→R→B19′.随着热循环次数的增加,正相变过程中Rs点升高,R相变温度范围变宽,Ms点降低;逆相变的相变温度都降低.In order to investigate the effect of thermal cycling on the transformation of laser-welded NiTi alloy, the laser spot-welded joints of Ti - 50. 6 at. % Ni alloy wire were made. The microstructure was observed by microscope and the effect of thermal cycling on transformation behavior was studied by differential scanning calorimeter （DSC）. The results show that, the fusion zone features dendrite structure, the heat-affected zone comprises coarse and fine equiaxial crystal. The transformation behavior of joint changes with thermal cycling, varying from B2→B19＇to B2→R→B19＇. With increasing thermal cycles, the R phase transformation start temperature increases, and the temperature region of the R phase is broadened. But the martensitic transformation start temperature decreases, and the reverse transformation temperature decreases with increasing thermal cycles.

关 键 词：NITI形状记忆合金 激光点焊 热循环 相变行为 

分 类 号：TG139[一般工业技术—材料科学与工程]