The sintering of master alloy-blended Ti6Al4V powder has been investigated to elucidate the mechanisms of sintering. Both blended powder compacts and diffusion couple samples were investigated using backscattered imaging and energy dispersive analysis to determine the phases present, and the diffusion path for sintering which has not been previously reported for this system. Transient liquid-phase sintering does not occur, and it is shown for the first time that the reason for the rapid sintering of this material in the temperature range of 1000–1150 °C is due to enhanced diffusion kinetics resulting from a combination of the concentration gradient and stress induced by a phase transformation in the ternary system. The results of this study have implications for the development of blended master alloy combinations in other powder metallurgy systems.