DEFORMABILITY IMPROVEMENT IN C15 NbCr_2 INTERMETALLICS BY ADDITION OF TERNARY ELEMENTS

摘要

As alloying elements to improve the high temperature deformability of the C15 NbCr_2 Laves intermetallics, V and Mo were selected, based on the criterion of the atomic diameter ratio between the component A and B atoms, i.e. R_A/R_B controlling the atomic free volume along the { 111} shear planes in the C15 AB_2 structure. The smaller value of R_A/R_B is expected to facilitate the shear deformation. By high temperature compressive tests, both elements were shown to be effective in improving the high temperature deformability. Addition of Mo to the C 15 NbCr_2 resulted in decreases in the 0.2/100 yield stress and also in the brittle-ductile transition temperature (BDTT), and was hence more effective than the addition of V to the C 15 NbCr_2.