Castability of Cu-Al-Mn shape memory alloy in a rapid investment casting process: computational and experimental analysis

Abstract

Comparisons between virtual prototyping and experimental results are notably beneficial for the development of investment casting processes. In this research, such a comparison aimed to study the castability of a Cu-Al-Mn shape memory alloy (SMA) in a modified centrifugal investment casting process that uses centrifugal force to inject the molten metal into the mold. Virtual prototyping was numerically simulated using ProCAST software applying a rectangular mesh part design. The real and virtual parts were examined for mold filling (castability), pore formation and solidification time. Using Whitlook's methodology, it was possible to validate the model created in the ProCAST software to simulate the modified investment casting process, detecting results regarding filling, solidification and porosity with a high degree of accuracy and reliability. In addition to the validation of the developed model, this work also presents estimated values for interface heat transfer coefficient (IHTC) of the metal/mold of aluminum bronze (Cu-Al and Cu-Al-Mn) alloys poured by gravity and centrifugation into plaster molds. Among the obtained values, the IHTC for the 86.7Cu-7.9Al-5.4Mn SMA were estimated at 535 W/m²K when poured by centrifugal force and 75 W/m²K by gravity. Ultimately, it was possible to verify that Cu-Al based shape memory alloy presents a high castability and a low cooling rate.