The production of nanocrystalline cobalt titanide intermetallic compound via mechanical alloying

A nanocrystalline cobalt titanide (CoTi) intermetallic compound has been produced by mechanical alloying (MA) of the elemental powders. In all MA experiments, the ball-to-powder weight ratio was 10:1. The phase evolution and microstructural changes of the powders during mechanical alloying were investigated by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy and microhardness measurements. The results showed that after an optimum mechanical alloying time of 12 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 1.1% was achieved. The study of the mechanism for the formation of the CoTi phase revealed that a composite structure with coarse lamellar-like components was formed with the dissolution of Ti in Co in the early stages of mechanical alloying. The resulting solid solution ultimately provided for the formation of nanocrystalline CoTi phase with the high microhardness value of about 580 Hv.

► At the ball-to-powder weight ratio of 10:1, CoTi formed after 12 h of MA.
► TEM revealed that the crystallite size of the CoTi was less than 10 nm.
►  The microhardness of the samples increased with MA time.