Papers by Keyword: Metal Solidification

Abstract: The six Mg-Li and Mg-Li-Al alloys in as-cast state namely Mg-4.5%Li, Mg-9%Li, Mg-12%Li, Mg-4.5%Li-1.5%Al, Mg-9%Li-1.5%Al and Mg-12%Li-1.5%Al were prepared and analysed. These alloys have been subjected to the thermal analysis (thermal derivative-analysis and dilatometry study), and the subsequent thermal assessment, mechanical properties and microstructures were studied. The heating and cooling dilatometric curves characterise by a linear reduction (alloys with 12wt.% of Li) and linear increase (alloys with 4.5wt.% of Li) in coefficient of linear thermal expansion as a function of temperature. No transitions in the solid state occur. Based on results of thermal derivative analysis a crystallisation process of Mg-Li and Mg-Li-Al alloys was proposed. Addition of aluminium in ultra-light Mg-Li alloys shows considerably improved strengthening without a reduction in grain size. Increasing the lithium content causes in an increase of hardness.

Abstract: In order to take into account the dynamic effects of molten metal during solidification, a methodology is presented to interface a metal solidification solver (coupled thermal mechanical metallurgical finite elements solver) with a specifically developed flow dynamics solver. (flow dynamics and thermics finite volume solver) The numerical set of tools is designed to be used for the simulation of bimetallic hot rolling mill rolls vertical spincasting. Modeling the industrial process for these products imply certain specifications on the numerical methods used, mainly due to the size of the geometrical domain, low Rossby & Ekman numbers, and a high Reynolds number.

Abstract: Direct simulations of solidification processes that account for all space and time scales are often beyond the reach of current computational power. To overcome this limitation micromacro approaches that incorporate the effects of small-scale phenomena into large-scale process models have been developed. An important small-scale solidification phenomenon is microsegregation —the redistribution of rejected solute components at the scale of the solid crystal morphology. This paper outlines a general microsegregation model that not only accounts for many of the critical small-scale phenomena in alloy solidification but also well suited as the micro component of a micro-macro model of metal casting. In the development of this microsegregation model, particular emphasis and testing is placed on alternative treatments of modeling the microscale solute diffusion in the solid phase—the so-called “back-diffusion.”