Non-equilibrium solidification of concentrated Fe-Ge alloys

The solidification of concentrated alloys containing ordered compounds is less well understood. These alloys often exhibit complex phase change like peritectic reaction during liquid to solid transformation. The Fe-rich part of Fe-Ge binary alloy system consists of several critical points and ordered-disorder transitions and can be used as a model system to study the effect of departure from equilibrium on the solidification microstructure. In order to understand the phase selection and morphological transitions, undercooling and recalescence behaviour; growth rate of the solidifying phases and microstructure need to be explored. In the present paper, we summarise the results obtained in several iron rich alloy compositions (Fe-(14-25) at.% Ge) using techniques of melt quenching, levitation and laser resolidification. These results provide insight to the current theories of dendritic growth and reveals possibility of a new pathway for phase evolution in peritectic alloys at high undercooling involving a massive transformation.