Numerical simulation of formation of grain structure and global heat transport during solidification of technical alloys in MSL inserts

Abstract

Microgravity experiments related to solidification of alloys as well as to the growth of semiconductor crystals are an important part for the future utilisation of the International Space Station. Large series of experimental pre-tests on the ground are necessary for each experimental proposal to evaluate the proper process parameters like optimum cooling rates, heater temperatures and cartridge design. An empirical procedure of process optimisation, however, is extremely time and money consuming due to the variety and complexity of the different experimental set-ups. Moreover, detailed information on the thermal field in the samples, which is necessary also for interpreting the results, is difficult to obtain. In this situation, numerical simulation of heat and mass transport processes can be used to overcome these problems. Computer modelling is nowadays an indispensable tool in industry for developing solidification equipment and processes. However, in the field of microgravity research numerical modelling was not systematically and consequently used for the development of furnaces and cartridge designs as well as for the definition of process parameters. In this paper a concept for the global modelling of alloy solidification taking into account the evolution of the grain structure in Material Science Laboratory (MSL) inserts is presented.