THE USE OF COMPUTERIZED THERMODYNAMIC DATABASES FOR SOLIDIFICATION MODELING OF FUSION WELDS IN MULTI-COMPONENT ALLOYS

摘要

Most engineering alloys contain numerous alloying elements and their solidification behavior can not typically be modeled with existing binary and ternary phase diagrams. There has recently been considerable progress in the development of thermodynamic software programs for calculating solidification parameters and phase diagrams of multi-component systems. These routines can potentially provide useful input data that are needed in multi-component solidification models. However, these thermodynamic routines require validation before they can be confidently applied to simulations of alloys over a wide range of composition. In this article, a preliminary assessment of the accuracy of the Thermo-Calc NiFe Superalloy database is presented. The database validation is conducted by comparing calculated phase diagram quantities to experimental measurements available in the literature. Comparisons are provided in terms of calculated and measured liquidus and solidus temperatures and slopes, equilibrium distribution coefficients, and multi-component phase diagrams. Reasonable agreement is observed among the comparisons made to date. Examples are provided which illustrate how the database can be used to approximate the solidification sequence and final segregation patterns in multi-component alloys. An additional example of the coupling of calculated phase diagrams to solute redistribution computations in a commercial eight component Ni base superalloy is also presented.