Synthesis and characterization of nanocrystalline CoTi intermetallic compound prepared by mechanical alloying

In the present investigation, the nanocrystalline CoTi intermetallic compound was synthesized by mechanical alloying (MA) of the elemental powders. In all MA runs, the ball-to-powder weight ratio was 5:1. The phase evolution and microstructural changes of the powders during mechanical alloying were investigated by means of X-ray diffractometry, scanning electron microscopy, high-resolution transmission electron microscopy and microhardness measurements. The results showed that after an optimum mechanical alloying time of 30 h, a CoTi intermetallic phase with the crystallite size of less than 10 nm, the particle size of about 10 μm and the lattice strain of 0.6% was achieved. The nanocrystalline CoTi intermetallic compound exhibited high microhardness value of about 480 Hv.

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► MA of Co–43 wt.% Ti powders led to the gradual formation of CoTi intermetallic.
► 30 h of milling was the optimum time for producing the CoTi intermetallic compound.
► After 30 h of MA, CoTi was obtained with the crystallite size of less than 10 nm.
► The achieved nanocrystalline CoTi exhibited a high microhardness value of about 480 Hv.