Prediction of macrosegregation in binary alloy solidification using a non-newtonian mushy model

WOS: 000167625700002The solidification of Sn-10%Pb alloy and subsequent macrosegregation patterns are numerically investigated with a continuum mixture model. The mathematical model is valid in the solid, mushy (solid + liquid) and liquid regions. A hybrid flow model is employed for the mushy region. This model assumes the mushy region behaves as a non-Newtonian fluid below a transitional solid fraction and as a porous medium thereafter. The positive and negative segregations formed during the solidification are successfully predicted

A review of the modeling of multi-phase phenomena in materials processing - I. Solid-liquid systems

WOS: 000167625700001This paper reviews the modeling of multiphase flow phenomena in liquid-solid materials processes. Three mathematical models are discussed, namely, two-phase, continuum-mixture and multi-domain models. Scaling and analytical solutions of the governing equations are given for some simplified situations. A linear stability analysis is also presented on convection in the mushy region in alloy solidification

Application of a hybrid model of mushy zone to macrosegregation in alloy solidification

WOS: 000172477900004Solidification of an aqueous ammonium chloride (NH4Cl-H2O) solution inside a two-dimensional cavity is numerically investigated using a continuum mixture mathematical model. The mushy region where solid and liquid phases co-exist is considered a non-Newtonian fluid below a critical solid fraction, and a porous medium thereafter. This critical solid fraction is chosen as that corresponding to the coherency point, where a solid skeleton begins to form. The numerical results show that the solidification of a hypereutectic NH4Cl-H2O solution is mainly characterized by the rejection of solute at the mushy region and double diffusive convection induced by the opposing solutal and thermal buoyancy forces. The mathematical model agrees satisfactorily with the available experimental and numerical data. (C) 2001 Elsevier Science Ltd. All rights reserved