Microstructure and mechanical properties of multiphase layer formed during thermo-diffusing of titanium into the surface of C17200 copper-beryllium alloy

In order to improve the tribological properties of beryllium bronze substrate, Ti/Cu diffusion coatings were prepared by deposition and thermo-diffusing process. The substrates were firstly deposited with Ti film by magnetron sputtering. And post diffusion process was conducted at 810 C for 4 h and then aged at 450 C for 1 h under hydrogen plasma atmosphere in cathodic cage plasma treatment (CCPT) system. The as-obtained coating was characterized by scanning electron microscope (SEM), X-ray diffractometer (XRD), microhardness tests, and pin-on-disk tribometer. The results show that the coating consists of Cu ₄ Ti, Cu ₃ Ti ₂ , and Cu (Ti) solid solution. The hardness of the coating has reached about 528 HV _0.01 , which is much higher than that of the substrate. The coefficient of friction decreased from 0.65 for the uncoated substrate to about 0.3 for the coated one. And the wear rate of coated samples decreased nearly 97% compared with the uncoated one, so the coated specimen has a much better wear resistance. The analysis of worn surface indicated that the coated beryllium bronze exhibited predominant oxidation wear behavior, whereas the uncoated one shown adhesive wear behavior.