The effect of mechanical treatment of TiNi powder on structure and phase composition

In this work, the study of the effect of mechanical treatment of TiNi powder on structure and phase composition is presented. The powder was processed in high-energy planetary ball mill for different time. It has been shown that the average particle size measured by scanning electron microscopy changes not monotonous after mechanical treatment, but form of particles changes. The coherently diffracting domain size decreases from 43 nm to 5 nm with increasing of mechanical treatment time that significantly less than the average particle size measured by laser diffraction method and the average particle size calculated from the obtained values of the specific surface. That is to say, the powder particles consist of several crystallites. The width of all peaks changes after 10 s of mechanical treatment that can correspond to an increasing of the defect density. The lattices parameters of all phases change not more than 0.8 % after mechanical treatment. Two processes compete during mechanical treatment, characterizing either brittleness or plasticity. Many defects appear during mechanical treatment stipulate a quasi-amorphous state with increasing of mechanical treatment time.