Densities of fcc nickel–iron alloys

Abstract

The room temperature densities of Ni-Fe (0 to 70 wt.-%) have been determined by X-ray diffraction and hydrostatic weighing. Swedish charcoal iron (kindly supplied by the British Steel Corporation) with main impurities (wt.-%): Mn 0.15, Si 0.07, P 0.03, and C 0.03 and 99.999% pure nickel were melted, rolled and folded, and remelted, in an argonarc furnace with a Ti getter. The alloy compositions (calculated from the batch weights) are shown in Table I. Lattice parameters were obtained using Fe-filtered Co radiation on filings smaller than 150 mesh which had been annealed for 30 min at 800°C in an evacuated glass tube and then air cooled. The data were analysed by a Nelson–Riley plot. Good agreement was obtained with the lattice parameter data of Bradley et al. although in each case the present results were smaller. The greatest difference was 0.00049 nm which occurred with the pure Ni, but on the alloys the agreement was much closer. Densities calculated from the lattice parameters are shown in Table I. Hydrostatic densities were obtained using boiled distilled water which was left in a chemical balance overnight to attain a steady temperature. Specimens were checked for surface cracks with a fluorescent penetrant and then degreased ultrasonically in CCl₄ before testing. Weighing on a chemical balance was accurate to ± 0.05 mg, and the density of the water was corrected for its temperature. The results are presented in Table I, and shown with other data in Fig. 1. It is seen that the densities calculated from the lattice parameters are always slightly larger than those obtained by weighing—a result which is as expected since the weighing method includes any lattice defects or porosity in its volume.