Concentration fields in the solidification processing of metal matrix composites

• Published in: International journal of heat and mass transfer 2002-10, Vol.45 (21), p.4251-4266
• Main Authors: Moussa, Bechir, Simpson, James E, Garimella, Suresh V
• Format: Article
• Language: English
• Subjects: Applied sciences; Binary alloys; Computer simulation; Electric conductivity of solids; Exact sciences and technology; Fiber reinforced metals; Fibre reinforced metals; Interfaces (materials); Metallic matrix composites; Metals. Metallurgy; Powder metallurgy. Composite materials; Production techniques
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/S0017-9310(02)00147-3

A numerical investigation of the solidification of a binary alloy (Al-1.0 wt.% Cu) around cylindrical fibers with different fiber layouts and thermophysical properties was undertaken to gain insight into the processing of fiber-reinforced metal matrix composites. The focus of this study was on solute transport and redistribution during the solidification process, and the resulting concentration fields in the solidified alloy matrix. Change of phase in the alloy was formulated using a modified version of the temperature-transforming method for the energy equation. A source term that accounts for the solute rejection at the interface was incorporated into the solute concentration equation to model solute redistribution at the interface. Detailed results were obtained from the numerical simulations of low-(alumina) and high-(copper) conductivity fibers in inline and staggered configurations. Effects of the fiber pitch (longitudinal spacing) and transverse spacing were investigated. Higher concentrations of solute were seen to accumulate around copper fibers than for alumina fibers. With an initial, uniform concentration of 1.0 wt.% Cu in the melt, the maximum-recorded solute concentration in the domain for alumina fibers was 1.26% while that for copper fibers was 3.11%. For inline fibers, increasing the fiber pitch beyond a critical value did not change the overall shape of the local solute distribution around the fibers: the critical pitch for alumina fibers was found to be roughly 2.5 fiber diameters while that for copper was 2 fiber diameters.