Solubility limits and constitutional defects in Laves phase intermetallics were investigated in the C15 HfCo2 system. Several binary alloy compositions, based upon Co2Hf, were characterized by means of optical and scanning electron microscopy, electron microprobe analysis, X-ray diffraction and density measurements. Rietveld refinement of X-ray diffraction scans was used to determine lattice constants, anisotropic strain parameters and atomic occupancies. Compositional trends were compared with predicted or calculated trends due to an antisite substitution or vacancy defect mechanism. Geometrical models and atomic-size factors were used to establish solubility limits and to furnish insight into defect mechanisms. The results of various

complementary experiments were consistent with antisite substitutions on both sides of Co2Hf stoichiometry.

HfCo2 Laves Phase Intermetallics – I. Solubility Limits and Defect Mechanisms. K.C.Chen, E.J.Peterson, D.J.Thoma: Intermetallics, 2001, 9[9], 771-83