Influence of grain size of nanocrystalline titanium on its dissolution intensity in aluminum

Using molecular dynamics simulations, this study investigates the influence of grain size of nanocrystalline titanium on its dissolution intensity in aluminum at various temperatures, compared to the dissolution of monocrystalline titanium. It is shown that the grain size in nanocrystalline titanium significantly affects the intensity of mutual dissolution of the components. This is explained by the fact that grain boundaries act as channels for accelerated diffusion, and as the average grain size decreases, the density of grain boundaries increases. In the case of grains on the order of several nanometers, the density of grain boundaries and the contribution of grain boundary diffusion are relatively high. For example, at a temperature of 800 K, which is significantly below the melting point of aluminum, dissolution in the model occurred more intensely for grain sizes smaller than 9 nm than for monocrystalline titanium at 1100 K — this temperature is not only 300 K higher but also corresponds to liquid aluminum. Thus, the nanocrystalline structure and high density of grain boundaries in titanium may be one of the reasons, alongside the energy stored in defects due to deformation, for the reduction in activation energy for the synthesis reaction in the Ti-Al system following mechanical processing of the initial mixture.