Pseudotwinning in indium-lead concentrated alloys

Pseudoelasticity caused by pseudotwinning in short-range ordered In-Pb alloys (6, 8 and 11.6 at.% Pb) is studied in the temperature range 1,7–180 K. The mechanical hysteresis parameters, namely, the thermodynamic stress $\tau_{\rm T}$ which provides the reversibility of plastic deformation and the friction stress $\tau_{\rm f}$ which characterizes the resistance offered by crystal lattice and its defects to twin boundaries motion are estimated. It is found that athermal processes determine the reversible deformation: the mechanical parameters $\tau_{\rm T}$ N $\tau_{\rm f}$ do not depend on temperature and strain rate. The stress $\tau_{\rm T}$ increases and the stress $\tau_{\rm f}$ decreases with increasing Pb content. One of the main conditions of the exhibition of superelasticity is the fulfillment of the inequality $\tau_{\rm T}> \tau_{\rm f}$