Hydrogen influence on plastic deformation mechanism of β-titanium alloys of Ti–Nb system

Abstract

The influence of hydrogen on the mechanism of cold plastic deformation at room temperature of β-Ti–Nb alloys with Nb content from 20 to 50 wt% is studied. It is shown that hydrogen increases the mechanical stability of the β-phase and hinders shape changes which occur due to a martensitic transformation or twinning. Hydrogen influences strongly the slip mechanism in the β-plane. The dislocation unpinning under hydrogen atmosphere during deformation causes the formation of `upper' and `lower' yield points. That causes the formation of a higher yield point during compression of the samples and leads to a strong location of deformation during tension tests. In general, hydrogen assists in lowering the deformation energy, and increases the ductility and mechanical instability of β-titanium alloys containing from 20 to 40% Nb.