Ultrafast healing of micro-pores in cold-sprayed CuCrZr-W composite coatings via high-frequency induction heating

Micro-pore healing in cold-sprayed composite coatings with hard particles remains challenging for achieving optimal performance. This work employs high-frequency induction heating (HFIH) to rapidly heal micro-pores (within 17 s) in a cold sprayed CuCrZr-W composite coating by leveraging current detouring and crowding at the boundaries of high-resistance W particles and micro-pores. During cold spraying, limited plastic deformation of CuCrZr particles creates micro-pores at particle interfaces. HFIH induces localized high current density at the CuCrZr-W interface, generating significant thermal and athermal effects. Joule heating elevates local temperatures, promoting rapid Cu grain growth and atomic diffusion, which leads to the shrinkage and partial healing of micro-pores. Furthermore, high current density drives atoms (such as Cr and Zr) accumulation at the interface, enhancing micro-pore filling, and forms a thicker amorphous layer at the CuCrZr/W interface through atomic diffusion, improving the interfacial bonding. As a result, the coating’s conductivity significantly rises from 20% IACS to 44% IACS, and shear strength between the coating and substrate increases from 169 MPa to 189 MPa.