Metallurgy in Space

Over the past five years, an application-oriented research strategy has been initiated by ESA to permit valuable microgravity research in a broad range of physical sciences. The main objective is to integrate ESA, national activities and industry into an overall European strategy, which will allow research to be performed aboard the International Space Station (ISS), as well as other microgravity platforms, like unmanned space capsules, sounding rockets and parabolic flights. A key area of microgravity research is centred on metallurgy in space. The principal aims of this research field are (i) to investigate various physical phenomena during solidification processes and (ii) to determine the thermophysical properties of important liquid alloys. A number of metallurgical sub-topics have been identified in the ESA research programme, including the columnar-to-equiaxed transition during solidification; metastable and non-equilibrium solidification; multiphase multicomponent alloy solidification; eutectic, peritectic, monotectic and intermetallic alloy growth; fluid flow effects on mushy zone formation; and the measurement of thermophysical properties of liquid alloys. This review paper will therefore highlight the theoretical, experimental and modelling efforts currently being undertaken in the ESA programme.