Activation Volumes For Nanocrystal Growth In Amorphous Nd3.6pr5.4fe83co3b5 At Different Temperatures

To understand the nanocrystallization process of amorphous Nd3.6Pr5.4Fe83Co3B5, activation volumes for the growth of nanocrystals in the alloy have been determined directly by measuring the rate constants varying with pressure at different temperatures. At T = 773 K, the activation volume for the growth of alpha-(Fe,Co) phase is determined to be (0.50 +/- 0.02)Omega, where Omega is the mean atomic volume of the alloy, and it increases slightly to (0.59 +/- 0.03)Omega at T = 823 K. The activation volume for the growth of (Nd,Pr)(2)Fe14B phase at T = 823K is determined to be (0.52 +/- 0.02)Omega. The effect of temperature on the activation volume for nanocrystal growth is discussed.