Designing of a thin Mo diffusion barrier towards strong and reliable Ti/Cu dissimilar brazing

Abstract

The dissimilar brazing of Ti and Cu has been recognized to be challenging owing to the affinity of forming brittle intermetallic compounds at joint interface. In the current investigation, it was demonstrated that such detrimental interfacial reaction products can be readily circumvented by employing a Mo diffusion barrier deposited on Ti substrate. Combining Mo interlayer and a Ag–Cu–Ti active filler alloy, intermetallic compounds free Ti/Cu brazed joints consisting of Ti–Mo solid solution, Mo interlayer and remnant braze can be obtained. As a result of the eradication of brittle phases, the resultant joints exhibit excellent structural integrity with bonding strength comparable to the parent material properties. Additionally, as a consequence of sluggish solid state diffusion at the Ti/Mo interface and limited dissolution of the Mo interlayer by filler alloy during brazing, the desirable joint microstructure can be reproduced within a wide range of bonding duration. Such results indicate that strong and reliable Ti/Cu dissimilar brazing can be achieved by the combination of a Mo diffusion barrier and Ag–Cu–Ti active filler alloy.