Effect of Mechanical Activation on the in situ Formation of TiB2 Particulates in the Powder Mixture of TiH2 and FeB

The in situ formation of TiB₂ particulates via an interface reaction between Ti and FeB powders was studied. The effects of mechanical activation by high-energy milling on the decomposition of TiH₂ and the interface reactions between Ti and FeB powders to form TiB₂ were investigated. Powder mixtures were fabricated using planetary ball-milling under various milling conditions. The specific ball-milling energy was calculated from the measured electrical power consumption during milling process. High specific milling energy (152.6 kJ/g) resulted in a size reduction and homogeneous dispersion of constituent powders. This resulted in a decrease in the decomposition temperature of TiH₂ and an increase in the formation reaction of TiB₂ particulates in the Fe matrix, resulting in a homogeneous microstructure of nanoscale TiB₂ evenly distributed within the Fe matrix. In contrast, the powder mixture milled with low specific milling energy (36.5 kJ/g) showed an inhomogeneous microstructure composed of relatively large Fe-Fe₂ B particles surrounded by a thin layer of Fe-TiB₂ within a finely dispersed Fe-TiB₂ matrix region.