The diffusion of platinum and gold in nickel measured by Rutherford backscattering spectrometry

Abstract

The diffusion of platinum and gold in nickel at relatively low temperatures (250–725 °C) was measured by Rutherford backscattering spectrometry (RBS). The diffusion profile of the noble metal in nickel was calculated from RBS spectra. This method takes fully into account the dependence of the energy losses of the backscattered particle along the inward and outward paths on the changing energy of the particle and the changing composition of the target. Diffusion coefficients are calculated from the measured diffusion profile. The dependence of the diffusion coefficient on temperature obeys the Arrhenius law. The activation enthalpies are 78.2 kJ mol -1 and 119.6 kJ mol -1 for the diffusion of platinum and gold respectively into nickel. The frequency factors are respectively 2.6 × 10 −9 cm 2 s −1 and 1.4 × 10 −7 cm 2 s −1. Experimental data suggest that diffusion along the grain boundaries is 2–3 times as fast as bulk diffusion.