MACROSEGREGATION PATTERNS IN MULTICOMPONENT NI-BASE ALLOYS

A mathematical model of the dendritic solidification of multicomponent alloys, that includes thermosolutal convection and macrosegregation, is presented. The model is an extension of one previously developed fo r binary alloys. Numerical simulations are given for ternary and quate rnary Ni-base alloys, and the evolution of macrosegregation during sol idification is studied. The results show that the segregation patterns vary greatly with cooling conditions, adopting several shapes and lev els of intensity. Calculations of segregation in rectangular molds and in molds with smooth and abrupt variations of the cross sections exhi bit significant differences in the distribution of macrosegregation du e to the change in geometry. In addition, the segregation patterns are found to be particularly sensitive to the values of the equilibrium p artition coefficients of the alloy components.