SOLIDIFICATION OF TERNARY METAL-ALLOYS .2. PREDICTIONS OF CONVECTIVE PHENOMENA AND SOLIDIFICATION BEHAVIOR IN PB-SB-SN ALLOYS

In Part I of this work, the continuum mixture model for binary alloys was extended to three component systems and used an idealized ternary phase diagram to provide the supplemental thermodynamic relations need ed to close the model. In this paper, the new model is applied to the solidification of four lead-rich Pb-Sb-Sn alloys. System-specific info rmation needed to close the model presented in Part I is extracted fro m the lead-antimony-tin phase diagram. Numerical simulations are perfo rmed to demonstrate similarities and differences between the macrosegr egation patterns and convective flows of these ternary alloys and of t wo component systems. Macrosegregation of the solutes is altered signi ficantly from the familiar patterns of the binary systems only when so lidification in the doubly saturated binary troughs occurs near the li quidus interface. If the secondary and tertiary crystallization occur deep in the mushy zone, the resulting microsegregation has only small effects on the final redistribution of solute. (C) 1997 Elsevier Scien ce Ltd.