Metastable and nanocrystalline polymorphs of magnetic intermetallics

Non-equilibrium processing of ordered magnetic intermetallic compositions is found to lead to the formation of high temperature phases and structures. Examples are given for transformations to high temperature phase crystal structures and for suppression of chemical long-range order and the superlattice that lead to disordered solid-solutions within the original crystal lattice. Saturation magnetization and Curie temperatures in the metastable polymorphs can be higher or lower than the ordered intermetallics depending on the crystal structure. Observation of low temperature spin-glass behavior in metastable polymorphs of concentrated binary intermetallics are also considered. Finally, it is shown that when magnetic contributions can be properly accounted for, the heats of formation of ordered intermetallics can be derived from simple DSC measurements of the heat of reordering.