Transition from superelastic to irreversible twinning in InPb alloys as a relaxation-like process

The reversible--irreversible twinning transition is investigated by detailed analysis of twinning parameters of superplastic In--Pb alloys in the transition range of temp.; single crystals containing 6 and 8 at.% are used. The experiments suggest that the transition from superplastic to irreversible twinning is a relaxation-like process, so far as it reflects the transition from the atomic order disturbed by deformation twinning to the state equilibrium in these conditions. The obvious similarity of the nature of superelasticity in the In--Pb alloys and the In--Ti and Au--Cd alloys displaying superelasticity in the martensitic phase is emphasized. It is suggested that relaxation of the crystal nonequilibrium structure arises from twinning through diffusion of atoms for distance close to the atomic spacing. 8 ref.--C.M.L.S.