Analysis of stacking faults in the Hf-V-Nb cubic laves phase

Abstract

It has been shown that increasing the Nb concentration within the cubic laves phase of a Hf-V-Nb alloy such that the composition is closer to a region of hexagonal laves phase stability increases the occurrence of stacking defects in the material. The stacking faults were shown to have intrinsic character by HREM analysis in contrast to alloys of lower Nb content. Although no direct measurement was made, the data are consistent with a reduced stacking fault energy of the cubic laves phase. Although a lower SFE in elemental fcc materials can increase deformation twinning, the implications for twinning in cubic laves phases (complex fcc) is unclear since intergrowths of hexagonal material may compromise polycrystalline ductility.