Laser joining of Mo and Ta sheets with Ti6Al4V or Ni filler

Joining of Mo to Ta is important in manufacturing of high temperature microwave device. However, it is difficult to weld these two refractory metals directly because of their limited weldability. This study presents a laser joining method of Mo and Ta using Ti6Al4V or Ni as filler metal to prevent the mixture of two base metals in molten pool. The bulk of the Mo and Ta remained solid and joined by the liquid filler metal since the melting point of filler metal is considerably lower than that of base metals, resulting in two interfaces formed in each joint. The tensile strength of the Mo/Ni/Ta joint fractured from Ni/Ta interface is 19% lower than that of Mo/Ti6Al4V/Ta joint broken at base metal of Ta due to the formation of IMCs. These results offer a reference to filler metals selection for the joining of Mo to Ta, and highlight a possible method when dissimilar joining of two hard-to-weld metals especially refractory metals.