THE INCOHERENT GAMMA GAMMA SOLVUS IN NI-AL ALLOYS/

Analysis of the kinetics of solute (Al) depletion during the coarsenin g of gamma' (Ni3Al) precipitates has been used in earlier investigatio ns to provide values of the coherent solubility of the gamma' phase in binary Ni-Al alloys. As demonstrated in recent experimental investiga tions, the coherent solubility is a function of the total concentratio n of Al in the two-phase alloy. Using the model of Ardell and Maheshwa ri to analyze the data on coherent equilibrium, the authors estimated the incoherent equilibrium solubility of the gamma' phase over the tem perature range 400 to 800 degrees C. The calculated incoherent solubil ity limits are 3 to 5% smaller than previously published measurements, the differences decreasing as the temperature increases. The authors argue that the calculations in this article provide the first estimate s of the incoherent solvus of the gamma' phase in Ni-Al alloys.