焊接工艺对瞬时液相焊接头组织及性能的影响

Effect of bonding parameters on microstructure and properties of transient liquid phase bonding joint

以Ni-Cr-B非晶薄片作为连接中间层,对Mar-M247镍基高温合金进行瞬时液相焊,采用光学显微镜（OM）、扫描电镜（SEM）、能谱仪（EDS）和硬度测试仪研究了焊接温度及时间对接头组织和性能的影响。结果表明：中间层和基体发生扩散反应,在保温时间不充分时,连接层内形成了非等温凝固区,其组成为镍基固溶相,富Ni硼化物和富Cr硼化物。在温度一定时,随着保温时间的增加,非等温凝固区宽度逐渐减小,最后形成完全等温凝固区,试样接头的断裂方式也由脆性断裂转变为韧性断裂。当保温时间一定时,升高焊接温度至1150℃,接头组织中非等温凝固区占比最小,力学性能最佳,极限拉伸强度为845 MPa,伸长率为11.5%。

Transient liquid phase bonding of Mar-M247 nickel based superalloy was performed with Ni-Cr-B amorphous foil as interlayer.Effect of bonding temperature and holding time on the microstructure and mechanical properties of joints were studied by using OM,SEM,EDS and Vickers hardness tester. The results show that diffusion reaction occurs at the interface between interlayer and base metal. When the holding time is insufficient,an athermally solidified zone forms,which is consisted of Ni solid solution phase,Ni-rich boride and Cr-rich boride. Under a constant bonding temperature,the width of the athermally solidified zone decreases with the increase of holding time,resulting in formation of completed isothermally solidified zone. The fracture mode also transforms from brittle fracture to ductile fracture with the increase of holding time. Under a constant holding time,the proportion of athermally solidified zone in joint area reaches the least when increasing bonding temperature to 1150 ℃,the optimal mechanical properties are obtained with 845 MPa ultimate tensile strength and11. 5% elongation.