Liquid-solid partition ratios in nickel-base alloys

Abstract

The equilibrium partition ratios of Al, Ta, and Cr in Ni-rich alloys of the Ni-Al-Ta-Cr system were experimentally determined by isothermally holding at a temperature in the liquid-solid range of the alloys followed by quenching. The partition ratios apply to equilibria between metls and γ phase (fcc) in the range of 1615 to 1694 K. It was found that the equilibrium partition ratios in this system depend mainly on the concentration of Ta. The equilibrium partition ratio of Ta varies from approximately 0.6 at dilute Ta to 0.85 at 17 wt pct Ta. For the same range of Ta contents, less variability is seen in the partition ratios of Al and Cr, which range from about 0.92 to 0.96. In addition to the partition ratios, the liquidus temperatures of the liquid in equilibrium with γ in the Ni-Al-Ta-Cr system were estimated with a multidimensional regression analysis. The experimental results reported herein are complemented by a compilation of partition ratios of many solutes in binary and multicomponent Ni-base alloys.