Nucleation and phase selection in undercooled melts: Magnetic alloys of industrial relevance (MAGNEPHAS)

Studies of phase selection and microstructure evolution in high-performance magnetic materials are an urgent need for optimization of production routes. Containerless solidification experiments by electromagnetic levitation and drop tube solidification were conducted in undercooled melts of Fe-Co, Fe-Ni soft magnetic, and Nd-Fe-B hard magnetic alloys. Melt undercooling under microgravity was achieved in the TEMPUS facility during parabolic flight campaigns. For Fe-Co and Fe-Ni alloys significant effects of microgravity on metastable phase formation were discovered. Microstructure modifications as well as metastable phase formation as function of undercooling and melt flow were elucidated in Nd-Fe-B. Modeling of solidification processes, fluid flow and heat transfer provide predictive tools for microstructure engineering from the melt. They were developed as a link between undercooling experiments under terrestrial and microgravity conditions and the production routes of magnetic materials

Exact analytical solution based on the vector potential technique for a conjugated hydrodynamic and joule heating problem in an electromagnetically levitated drop

The paper presents exact analytical expressions for Lorentz force density and Joule heat power induced by an external alternating electric current inside a magnetically levitated drop. These expressions have been written as the source right-hand-side terms in the analytic solution for the stream function and temperature which were derived previously using Van Dyke’s series-truncation technique. For the first time, a close-form analytical solution for the conjugated hydrodynamic and thermal problems for a spherical drop surrounded by gas was obtained. This method is a robust and fast approach for the evaluation of fluid flow and temperature fields in levitation experiments on rapid solidification of metals.status: publishe