单晶高温合金的过渡液相扩散焊

Transient liquid phase( TLP) diffusion bonded single crystal superalloy

为了探明单晶过渡液相(TLP)扩散焊接头组织与性能的关系,采用扫描电镜(SEM)研究接头微观组织,并进行力学性能测试.结果表明,接头由连接区和基体区所组成.当等温凝固过程未完成时,连接区由等温凝固区和快速凝固区组成,而等温凝固区主要由γ和γ'相组成,快速凝固区主要是由共晶组织组成.当等温凝固完成而固态均匀化过程不充分时,连接区由等温凝固区和分布在接头中心的硼化物相组成.采用低温等温凝固,高温固态均匀化的焊接工艺可以获得高性能的接头.

Microstructure of transient liquid phase( TLP)diffusion bonded single crystal superalloy joint was investigatedby using scanning electron microscopy( SEM),and mechanical properties test of joint was carried out,for obtaining relationship between microstructure and mechanical properties of joint. The results showed that the joint was contained by the bonding zone and parent material zone. Before isothermal solidification process was finished,the bonding zone was contained isothermal solidification zone and rapid solidification zone. Metallographic examination revealed that isothermal solidification zone consisted of γand γ' phases,rapid solidification zone consisted of eutectics.When homogenization process was not enough under the condition of finishing isothermal solidification process,the bonding zone would contain isothermal solidification zone and borides at the interface. It is effectively improved for mechanical properties of joint by welding procedure of 'isothermal solidification at relatively low welding temperature and homogenization at relatively high welding temperature'.