Anisotropy of mechanical properties in directionally solidified Nb-Si alloys at room temperature compression

Abstract

The room-temperature compressive strength and deformation mechanisms in directional solidified Nb-Si alloy with different orientations were studied. The Electron Backscattered Diffraction (EBSD) experiment further explained that the orientation relationship between the Nbss phase and the α-Nb5Si3 phase is [001] Nbss // [001] α-Nb5Si3, (110) Nbss // (110) α-Nb5Si3, and the corresponding relationship between the material crystal structure and macroscopic spatial coordinates was established. The anisotropy of mechanical properties and failure mode in the alloys are attributed to the phase structures which are the long rod-like morphology of the α-Nb5Si3 phase growing along [001] and the spatial asymmetry of a single (110) Nbss // (110) α-Nb5Si3 phase interface. The Tsai-Hill criterion was applied to explain the anisotropy of the compressive strength of alloy at an angle to the direction of the heat flow. In addition, phase boundary separation was considered to be an important reason for the higher plasticity exhibited by the [100] compression orientation.