Microstructural investigation of plastically deformed Pb(1-x)Snx alloys:: an X-ray profile-fitting approach

A detailed X-ray line-profile analysis is presented on five compositions of Pb-Sn alloys in the face-centred cubic (f.c.c.) alpha phase; Analysis has been performed within the framework of the Warren-Averbach method and the Williamson-Hall method through a profile-fitting algorithm assuming a pseudo-Voigt(pV) profile shape function convoluted with an asymmetric function. The effect of cold-working on the alloys is analysed in terms of defect-related parameters and defect distribution. The alloys decompose beyond the composition. Pb-13.2 at.% Sn. Cold-working produces very weak structural broadening in Pb-Sn alloys, along with negligible incidence of deformation-fault probability. However, the presence of the Sn-rich beta phase enhances the fault probability. The plot of ln(epsilon(2))(1/2) versus Int is a straight line and the slope is around -0.26 to -0.43; indicating that the strain-broadened profile is intermediate between a Gaussian and a Lorentzian profile. The origin of the 'hook' effect in the size Fourier plot is attributed to non-Gaussian strain distribution or strain gradients in the diffracting columns; The effect of recovery is noticeable and is probably due to polygonization. Furthermore, the rate of recovery is greater in Pb-Sn alloys compared to Pb-Sb alloys for identical solute concentrations.