Investigation on the surface layer characteristics of shot peened titanium matrix composite utilizing X-ray diffraction

The surface layer characteristics of shot peened (TiB + TiC)/Ti–6Al–4 V composite are investigated using X-ray diffraction line profile analysis. The structural breadth, domain sizes, microstrain and dislocation densities of the matrices and composite are obtained. The results show that the domain sizes are refined after shot peening, and the dislocation densities are increased sharply in the near surface layer, which result from the high kinetic energy of shot balls in the process of shot peening. Comparing with the calculated results of the matrices and composite, it can be found that the microstructure variations of matrices are more severe than compositeʹs, which is ascribed to the effect of reinforcementsʹ resistance to the surface layersʹ deformation. Besides, the distributions of residual stresses and microhardness with different shot peening intensities and reinforcement volume fractions have been discussed, and the effects of reinforcements and shot peening intensities have been indicated. According to above detailed discussions, the results reveal that shot peening is an essential process of improving the surface properties of titanium matrix composite.