Liquid-solid partition ratios in nickel-base alloys

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 quench ing. The partition ratios apply to equilibria between melts and gamma phase (fcc) in the range of 1615 to 1694 K. It was found that the equilibrium pa rtition 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 pet Ta. For the same range of Ta contents, less variabi lity 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 gamma in the Ni-Al-Ta-Cr system were est imated with a multidimensional regression analysis. The experimental result s reported herein are complemented by a compilation of partition ratios of many solutes in binary and multicomponent Ni-base alloys.