A study for pre-processing of Nb diffusion in Nb-N layer by double-glow plasma alloying

In this study, a Nb layer was deposited on Ti-6.5Al-2Zr-1Mo-1V alloys by the double glow plasma alloying technique and the effect of pre-diffusion of Nb in the Nb-N films on microstructure and mechanical properties was analyzed. The structure of pre-diffusion samples is characteristic of a thick interdiffusion layer and a nitride gradient layer. This novel structure is beneficial for relieving the residual stress at the preparation process and the stress field were redistributed during loading because the properties were changed gradually along with the depth. In addition, the pre-processing of diffusion is believed to effectively increase the nitrogen permeation rate and further alter the Ti diffusion path, subsequently achieving the changed structure and phase composition of the Nb-N co-diffusion layer. Ball-on-disc wear tests were carried out at different loads for pre-diffusion and co-diffusion samples. The pre-diffusion sample and counter-ball all showed slighter damage than that of the co-diffusion sample. (C) 2019 Elsevier B.V. All rights reserved.