A physical explanation of this phenomenon is possible based on an analysis of the sintering mechanism of highspeed
steel powder with an activating addition of Ni − B [9]. Considering that the appearance of liquid phase in the
studied range of temperatures is due to the formation of a low-melting eutectic in the Ni − B system, it can be expected
that with decreasing initial density the area of particle interphase contacts at which melting occurs decreases. This, in
turn, decreases the amount of liquid phase which is formed resulting in a decrease in the rate of processes such as
particle regrouping due to capillary forces as well as volume densification by recrystallization via the liquid phase.