The influence of temperature on slip and twinning in uranium

Abstract

The deformation modes of α-uranium have been studied by performing mechanical tests on single crystals prepared by both the phase shift and the strain-anneal methods. The critical resolved shear stresses for slip on the systems (010)[100], (001)[100], (110)[l1̄O] and (021)[11̄2] have been determined over a wide range of temperatures. The formation of twins on the systems "{197}" and (130) is facilitated by prior slip and the results indicate a pole mechanism involving 1 2 [11̄0] slip dislocations for the lateral growth of (130) twins. Lastly experiments on polycrystalline uranium support the hypothesis that the thermally activated deformation mechanism responsible for the temperature dependence of the flow stress is the overcoming of the resistance of the crystal lattice to the passage of dislocations. © 1971.