Premixed TiC–Ni composite powder prepared by mechanical milling of Ti–Ni alloy/graphite mixture and subsequent heat treatment

• Gibbs free energies of formation of (Ti,Ni)C were obtained from first-principles calculations.
• Thermodynamic instability and decomposition of the (Ti,Ni)C phase were investigated.
• (Ti,Ni)C phase was formed by mechanically alloying Ti-Ni alloy and graphite.
• TiC-Ni powder with Ni was obtained by decomposing the (Ti,Ni)C phase.

The non-equilibrium (Ti,Ni)C solid-solution phase was prepared by mechanical milling of a Ti–Ni alloy/graphite mixture. The formation of the non-equilibrium (Ti,Ni)C solid solution was confirmed by X-ray diffraction. The (Ti,Ni)C solid-solution phase was found to decompose into TiC and finely dispersed Ni during the heat treatment in vacuum obviously due to the thermal instability of the non-equilibrium phase. The instability of the (Ti,Ni)C phase was clearly demonstrated by the consideration on the Gibbs free energy of formation of the phase. This new method allows the production of premixed TiC–Ni composite powder having a fine and uniform composition which may provide enhanced properties over the conventionally mixed TiC–Ni powder.

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