Laser welding of Ti6Al4V assisted with nanostructured Ni/Al reactive multilayer films

In this paper, the nanostructured reactive multilayer films (RMFs) are used as the intermediate layer to assist laser welding of Ti6Al4V alloy. During the welding process, the heat of the laser ignites the RMFs, and the heat released by the RMFs reaction instantaneously reaches the liquidus temperature in the center of the joint. This new joining method is helpful in reducing the laser energy input, minimizing the increasing brittleness and reducing strength effect of heat affected zone of the titanium alloy base material, and increase the joint strength of welds. The experiment confirmed that the joint with the Ni/Al RMFs as the intermediate layer can achieve a shear strength of 396 MPa at 700 W laser power, which is 3 times as high as that of the direct laser welded joints without using Ni/Al RMFs at the same power. Moreover, the Ni/Al RMFs as an intermediate layer can reduce the laser power required for welding by 10-20% without lowering the joint strength. (C) 2019 The Authors. Published by Elsevier Ltd.