High-temperature deformation of the NbCr2-based Laves intermetallics in Nb-Cr-V and Nb-Cr-Mo alloy systems

High-temperature deformation of the C15 NbCr2-based intermetallics in ternary Nb-Cr-V and Nb-Cr-Mo alloy systems is observed in terms of microstructural and compositional effect, by compression testing and transmission electron microscopy (TEM). The observed 0.2% yield stress and stress-strain curve were largely dependent on the equilibrating b.c.c. phase (or the C15 phase), their volume fraction and morphology. Among the observed alloys, the Nb-Cr-Mo alloys consisting of the C15 phase and 'Nb-rich' b.c.c. phase showed slightly enhanced 0.2% yield stress and largely decreased brittle-ductile transition temperature (BDTT) in comparison to the unalloyed single-phase C15 NbCr2 alloy, indicating a better high-temperature mechanical property with a favorable balance of strength and fracture toughness. TEM observation indicates that high density of dislocations are observed above BDTT in both constituent phases in both alloy systems. Also, the Burgers vector and morphological feature of dislocations are determined. (orig.)