The Crystal Structure of Silver-Palladium and Silver-Gold Alloys

Crystal Structure of Silver, Gold and Palladium and of Ag-Au and Ag-Pd Alloys.—Thin ribbons of the pure metals and of seven binary alloys of each series were prepared by fusing into small ingots and then swaging, drawing and rolling to thicknesses of from 1/400 to 1/200 cm. The x-ray diffraction patterns were photographed by allowing the K-radiation of Mo to fall for 8 to 20 hours on each ribbon. It was found that all these metals and alloys have their atoms arranged in face-centered cubic lattices. The parameter $a$ of each lattice, the edge of the cube, has the values 4.08 × ${10}^{-8\mathrm{}}$, 4.075 × ${10}^{-8\mathrm{}}$ and 3.90 × ${10}^{-8\mathrm{}}$ cm. for pure Ag, Au and Pd respectively. For the Ag-Pd series, the parameter is nearly a linear function of the atomic per cent. of either component and this is also true for the Ag-Au series except that for the alloys with 30, 40 and 60 per cent. Ag the values of $a$ came out one per cent. too high. These results are for the most homogeneous and isotropic condition and are believed to be correct to within about 1/3 per cent. The effect of annealing at from 830 to 940° C. for an hour or more in vacuo was to increase the size of individual crystals, to render them more homogeneous and to make their orientations more isotropic. The effect of moderate cold working, rolling, pressing or hammering is to reduce the size of the individual crystals and to make them less isotropic.