Effect of Microstructural Variations Developed by heat Treatment On the Mechanical and Electrical Properties of (Pb-1.5 wt % Sb)

Abstract

The purpose of the present work is to investigate the effect of microstructural variations of the annealed (Pb-1.5 wt % Sb) alloy during the phase transformation, on their mechanical and electrical properties. Creep tests on the studied alloy (slow cooled) were made under different constant stresses ranging from 12 M Pa to 15 M Pa near the transformation temperature. Transient and steady state creep of this alloy showed a transition point at 443K. The transient creep parameters (β and n) were found to change with the applied stress and ageing temperature. The value of the time exponent(γ) was found to be 0.45, the activation energy of both the transient and steady state creep was found to be 42 kJ/mole and 52kJ/mole respectively above 443K. It was found that the strain rate sensitivity parameter (m) has the values ranging from 0.17 to 0.35. The microstructure of the deformed alloy samples were investigated by : X-ray diffraction technique which showed that the residual internal lattice strain was at 443K. Transmission electron microscopy and electron diffraction results showed good agreement with the Xray analysis. The dependence of the resistivity changes on the ageing temperatures were also studied. The activation energy of the precipitation process was found to be ranged from 0.07 to 0.09 ev, below and above 443K respectively.