The effects of orientation, temperature and strain rate on deformation of Fe−0.16 wt.% Ti single crystals

Abstract

The orientation dependence of the critical resolved shear stress (CRSS), of the activation volume V ∗ and of the activation enthalpy ΔH, for Fe−0.16 wt.% Ti single crystals were investigated at temperatures between 77 and 473 K. Three orientations were chosen so that slip could be examined on {110} and {112} in the twinning and antitwinning directions. In contrast with ZrH 2-purified Fe crystals the CRSS of the FeTi crystals is only slightly dependent upon orientation. There is no apparent orientation dependence of V ∗ and δH. The data for the FeTi crystals support a lattice-hardening mechanism as controlling low temperature deformation. The pronounced orientation dependence of the CRSS, V ∗ and ΔH in ZrH 2-purified crystals may be due to a higher concentration of interstitials, as compared with FeTi crystals. The only apparent effects of precipitates in the FeTi crystals is to increase the amount of nonuniform deformation after yielding, thereby increasing the work-hardening rate, and to reduce ductility. The results of this study indicate that although Ti-gettered Fe is representative of an interstitial-free Fe in the region of yielding, its work-hardening characteristics are considerably different from those of purer Fe.