Comprehensive enhancement of the mechanical and thermo-mechanical properties of W/Cu joints via femtosecond laser fabricated micro/nano interface structures

W/Cu joining is key for the fabrication of plasma facing components of fusion reactors, which however is very challenging due to the low bonding strength and high W/Cu interface thermal stress as a result of the immiscible nature of W-Cu binary system and thermal expansion coefficient mismatch between W and Cu. In this paper, we proposed a method for comprehensive enhancement of the mechanical and thermo-mechanical properties of W/Cu joints based on femtosecond (fs) laser fabricated micro/nano interface structures. Four kinds of surface structures, namely pristine structure, nano ripples, micro-cubes and micro-pits were fabricated on W by fs laser ablation and introduced into W/Cu joining interface by hot pressing joining at 1000 degrees C, 80 MPa. The micro/nano interface structures contribute to significant enhancement of the tensile strength, shearing strength and thermal fatigue life of the W/Cu joints, which reach 101.58 MPa, 186.47 MPa and > 800 thermal cycles, increased by about 150%, 320% and 400% compared with W/Cu joints with pristine interface structure. This research provides an approach for enhanced joining between dissimilar materials, including but not limited to W and Cu.