Ti／Al扩散焊的接头组织结构及其形成规律

以TA2和L4为焊接材料进行扩散焊，结合剪切断口形貌，XRD分析，SEM分析和接头强度测试，研究了Ti／Al扩散焊的接头形成规律。结果表明，接头形成过程包括互扩散形成冶金结合、冶金结合区生成新相、新相颗粒长大连接成片层、新相片层按照抛物线规律生长4个阶段。TiAl3是扩散反应的初生相，且在较长时间内是唯一生成相。它的生成具有一定延迟时间tD，tD受温度影响很大。接头强度取决于扩散区中冶金结合的程度及界面结构，在TiAl3新相连接成片层之后，接头强度达到甚至超过L4型Al母材。接头剪切断裂发生在界面扩散区的Al侧或Al母材内部。

Structure and Forming Process of the Ti/Al Diffusion Bonding Joints

Structure and forming process of the Ti/Al diffusion bonding joints were studied by means of scanning electron microscopy (SEM), X-ray diffractometry (XRD) and shear strength measurement. The TA2 and L4 were used as bonding couples. The results showed that the forming process of joints included four stages. The primary and unique phase was TiAl3 from the diffusion reaction for long time. There was a delay time tD before TiAl3 appeared, mainly affected by temperature. The joint strength depended on the metallurgical combination percentage and interface structure of diffusion zone, reaching or even exceeding the strength of L4 when the TiAl3 formed like sheet and layer. The shearing fracture of joints occurred on the interface of Al and diffusion zone or in the Al-based metal.