The change of phase composition and hardness at vacuum annealing of nitrides of Zr, Mo, Ti and Cr metals deposited on T15K6 hard alloy

The change of phase composition and hardness of zirconium, molybdenum, titan and chromium nitrides formed on T15K6 hard alloy at isochronous annealing in the temperature range of 670-1270 K were studied. The coatings on T15K6 hard alloy by cathodic arc deposition using one or double metals in nitrogen atmosphere were formed. The phase compositions formed with one metal using were mononitrides ZrN, TiN or double phase systems Mo2N+Mo, Cr2N+Cr. The using of two metals during deposition were produced of (Zr,Mo)N and (Ti,Cr)N solid solution. The decrease of hardness (by a factor of 2-3) mononitrides coatings after vacuum annealing correlates with the decrease of width of (111) diffraction peak. It was shown that during annealing the decay process of (Ti,Cr)N solid solution began at 1170 K and finished at 1270 K with creation of TiN and Cr2N nitrides. The coating of (Zr,Mo)N was possessed maximum thermal stability, the phase composition and hardness of which don't change during vacuum annealing at 670-1170 K temperature range. (authors)