Synthesis of nanocrystalline Ti(C,N) powders by mechanical alloying and influence of alloying elements on the reaction

The nanocrystalline Ti(C,N) powders were synthesized by mechanical alloying (MA) from the mixture of pure titanium, graphite and titanium nitride. The influence of nickel and molybdenum additions on the reaction was also studied. The phase transformation and powder morphology characteristics were studied further by using XRD and TEM. It was found that nano-sized Ti(C,N) powders were fabricated by mechanical alloying for 20 h at a ball-to-powder weight ratio of 30:1 and rotational speed of 400 rpm in planetary ball mill. The solid reaction included two stages: at the first stage, carbon atoms diffused into the titanium and formed Ti(C) supersaturated solid solution, then carbon atoms reacted with titanium to synthesize TiC; at the second stage, C and N atoms interdiffused, then Ti(C,N) solid solution was synthesized. Moreover, 10 wt.% nickel or molybdenum additions in the mixture could accelerate the synthesis of nanometer Ti(C,N) powders. The accelerating efficiency of Ni was superior to that of Mo.