Characterization of δNi₂Si Precipitates in Cu–Ni–Si Alloy by Small Angle X–Ray Scattering, Small Angle Neutron Scattering and Atom Probe Tomography

Abstract

The strength of Cu–Ni–Si alloy can be improved by finely dispersing a Ni–Si–based compound as a precipitate into the Cu parent phase by heat treatment. In order to investigate the strengthening effect of the precipitate, quantitative evaluation of the size distribution and dispersion state is necessary. In this work, we utilized transmission electron microscopy, small–angle X–ray scattering (SAXS), small–angle neutron scattering (SANS), and atom probe tomography to analyze this Ni–Si precipitated phase. The atom probe tomography results showed two types of the diffusion layers at the interface between the Cu parent phase and the precipitated phases. The alloy contrast variation method based on the difference of SAXS and SANS intensity in absolute units also suggests that the δNi₂Si precipitates are distorted.