Phase stability and defect structure of the C15 laves phase Nb(CR, V)_2

摘要

Vanadium alloyed C15 laves phase based on NbCr_2 and phase equilibria in the Nb-Cr-V sys- tem have been studied, focusing on the physical metallurgy and defect structures of the C15 phase. Based on the Nb-Cr-V phase diagram established in this work, the defect structure/mechanism in the ternary C15 Laves phase is investigated using a combination of metallography, SEM/EDS, TEM/ALCHEMI, and X-ray powder diffraction. It is found that the C15 phase field of NbCr_2 is extended by V alloying up to More than 30 at./100 V and V substitutes exclusively on the Cr site instead of the Nb site, although the Atomic sizes of the constituent elements indicate r_Cr < r_v < r_Nb.