Supersaturation of the Al2Y Laves phase by rapid solidification

Intermetallic phases often appear to exhibit a restricted compositional range of stability essentially limited to the stoichiometric value. However, there are important exceptions, such as B2 and L12 phases, where relatively wide fields of compositional stability develop. In the well-known B2 phases, such as NiAl, the operation of different defect mechanisms has been extensively documented and has an important impact on the mechanical behavior. The Laves phase class of intermetallics is a good example of a class where most representatives are essentially stoichiometric. However, there are important exceptions, such as NbCr2, where the solubility range is several percent. Although there are a larger number of Laves phases than B2 phases, relatively little is known about the possible defect structures that may be associated with solubility at off-stoichiometric compositions. If the intrinsic stability of a structure allows for departures from stoichiometry, then it may be possible to access even greater levels of departure by rapid solidification processing (RSP). An early report for the Al2Y Laves phase indicates that some departure from stoichiometry is possible during RSP. An assessment of the extent of metastable solubility for Al2Y and an analysis of the intermetallic solubility behavior are reported in the current work