Effect of Ni addition on the growth of W grains in Ni-Fe-W liquid matrix at 1490 ℃ has been investigated. Powder mixtures of 91.8w/o W-3 w/o Ni-5.2 w/o Fe were sintered for 1.5h until W grains grew considerably. Then each specimen was resintered for various times up to 20.5h after adding some Ni powder to make the composition of 88 w/o W-7 w/o Ni-5 w/o Fe. Newly formed equilibrium phase and original grain are differentiated by strong etching. After Ni addition, the grain size distribution has broadened, indicating that the solution of original small grains was retarded, therefore resulting in sluggish grain growth rate of the system. The thermodynamic consideration of growth kinetics showed the solution behavior of a grain could be explained by molar free energy of the grain. The dissolution rate of the original grain whose molar free energy is lower than the equilibrium phase grain, is retarded.
