Changes in the heat of melting of a superelastic eutectic Sn–38 wt % Pb alloy due to preliminary plastic deformation

The effect of an external compressing stress applied in the process of heating from room temperature to the preeutectic temperature on the specific heat of melting of an alloy Sn–38 wt % Pb has been investigated. The chosen stress range of 0–7.5 MPa includes stresses at which the alloy manifests superplastic properties. The experiments were conducted using the differential thermal analysis method. For the first time, a nonmonotonic dependence of the specific heat of melting of superplastic eutectic alloys on the magnitude of applied stress has been detected. These results have been explained by the metastability of the initial phase state of the alloy and by the stimulating influence of the plastic deformation depending on the level of external stresses on the processes providing a transition of the alloy to the equilibrium state.