On melting characteristics of bulk Al-7039 alloy during in-situ microwave casting

Metal casting is a melting-based multi-step primary manufacturing process. Melting involves interaction of the source energy with the target metal (or, the alloy/composite) and the process has significant influence on processing economy and environment. Use of microwave energy for melting of metals or alloys is not common owing to insufficient data in the field. This paper reports on in-situ microwave casting of Al-7039 bulk alloy using microwave radiations at 2.45 GHz and 1400 W. A 3-D model of the process was generated using COMSOL multiphysics software tool. Simulations were carried out to study the thermal history of the metal during melting. The temperature profiles obtained through the experimental trials and simulation were analyzed and found to be in reasonable agreement. The simulation results were obtained for varying power and location of the mold assembly. The possible outcomes were evaluated in terms of melting time, non-uniformity, average heating rate and energy required to melt the charge. The role of electric field distribution inside the microwave applicator and temperature distribution in the charge play important role in hot spot formation and rise in temperature in the charge. The influences of power and mold assembly location were found significant in rapid melting of the alloy. The simulation results showed that the heating of the bulk metal is more rapid and uniform at higher power levels and at specific locations of the mold assembly. (C) 2016 Elsevier Ltd. All rights reserved.