相变-扩散钎焊工艺焊接接头缺陷分析

Analysis of transformation-diffusion brazed joint

相变 -扩散钎焊是作者提出的一种将相变超塑性扩散焊与扩散钎焊结合起来的新型复合工艺 ,它具有所需温度循环次数少 (与相变超塑性扩散焊相比 )、高温停留时间短但扩散效率高 (与扩散钎焊相比 )、改善热影响区组织 (与弧焊和扩散钎焊相比 )等优点。针对其典型接头的界面接合形貌及缺陷 ,采用扫描电镜及能谱仪进行了分析。结果表明 ,界面接合良好 ,未观察到片状夹杂物、气孔及未焊合。而缺陷具有如下主要特点 :存在于距离界面内部有一定距离的残留中间层内 ,并不在界面上 ;并非夹杂而是孔洞 ;尺寸远小于晶粒尺寸 ;稀疏且错落排列。

Transformation-diffusion brazing is a brazing method combining transformation superplastic diffusion bonding with diffusion brazing. By this method, the numbers of thermal cycle can be reduced, the diffusion efficiency can be raised, and the microstructure of heat affected zone can be improved. In order to clarify the defects and interface micrograph in transformation-diffusion brazed joint, the joint is examined by SEM and EDS. A sound bonded interface is obtained without sheet inclusion, pore and unbending. The defects exist in the residual interlayer apart from the bonded interface. The size of cavity is much smaller than that of grain, and the cavities are sparsely arranged with dislocation. It is found that the cavities are CO pores caused by carbon reduction.