Super-elastic titanium alloy with unstable plastic deformation

Abstract

Here we report a non-toxic β -type titaniumalloy exhibiting unstable elastic and plastic deformation behavior. Elastic instability leads to remarkable elastic softening, i.e., the decrease of incipient Young’s modulus with slight pre-straining. In spite of partial recovery during room-temperature aging, a stable modulus of 33 GPa matching that of human bone can be maintained. Plastic instability causes highly-localized deformation which is very effective in grain refinement but contributes little to strength. We thus obtain soft nanostructured metallic materials (NMMs): The flow stress increases by only ∼ 5.5 % as coarse grains are reduced to below 50 nm , in contrast with several times increase for previously-reported NMMs.