Evaluation on Mechanical Properties and Electrical Contact Behaviors for Au/Ni Composite Coating by Experiment and Finite Element Method

Gold coatings are the most widely used protective layer for resisting surface oxidization and corrosion in various complex environments. However, the extremely low hardness, inferior load‐bearing capacity, and lack of an effective strategy for evaluating the elastic‐plastic behavior of gold coatings have greatly limited their further application. The main aim of this work is to investigate the effect of Ni doping on the microstructure, mechanical properties, and electrical contact stability of a coating based on an experimental method and finite element simulation. The strain‐hardening exponent model of the coating is established by employing a reverse analysis method based on the nanoindentation experiment until the reverse and forward loading curves are consistent, thereby determining the yield strength. The results indicate that Ni doping is conducive to enhancing the mechanical properties under the premise of ensuring low contact resistance. The hardness (3.3–4.2 GPa) and yield strength (524.3–689.8 MPa) of the Au _{1− x} Ni _x composite coating with a Ni content of 4 at–8 at% is more than twice as high as that of pure Au. The electrical contacts deposited by the Au _{1− x} Ni _x coatings maintain a low contact resistance range (1.12–3.29 mΩ) at a contact force of 10 gf.