X-Ray Diffraction Study of the Effects of Solutes on the Occurrence of Stacking Faults in Silver-Base Alloys

Abstract

The addition of the solutes cadmium, indium, and tin to silver increases the probability of deformation faults α in filings from 3×10−3 in pure silver to a maximum value of 45×10−3 at the highest concentrations of solute. In addition, the twin fault probability β measured from center of gravity displacements varies from 10×10−3 for pure silver to 30×10−3 for the alloys highest in tin or indium concentration. Lattice parameters ahkl were determined from all available reflections of the cold-worked and annealed specimens and plotted as a function of cos2θ/sinθ. By relating the large scatter of the individual ahkl to the occurrence of deformation faults in the deformed material, the true lattice parameter, a0(CW), and the deformation fault probabilities α of cold-worked materials could be determined. There was an apparent decrease in lattice parameter of the deformed Ag-Sn alloys which was largest (∼0.1%) for the greatest tin concentration (Ag-9%Sn). Using Fourier analysis of line profiles, the effective particle sizes (De)hkl and root mean square strains [〈εL2〉av]hkl½ were determined. The measured effective particle sizes were anisotropic [(De)111/(De)200=1.7] and are primarily a consequence of deformation and twin faulting. The values for the compound fault probability (1.5α+β) from peak shift and asymmetry and from anisotropic particle sizes, i.e., from peak broadening, agreed rather well.