Characterization of δNi<sub>2</sub>Si Precipitates in Cu-Ni-Si Alloy by Small-Angle X-ray Scattering, Small-Angle Neutron Scattering, and Atom Probe Tomography

The strength of a Cu-Ni-Si alloy can be improved by finely dispersing Ni-Si-based compounds as precipitates into the Cu matrix through heat treatment. This requires quantitatively evaluating the size distribution and dispersion state to investigate the strengthening effect of the precipitate. In this work, we utilized transmission electron microscopy, small-angle X-ray scattering (SAXS), small-angle neutron scattering (SANS), and atom probe tomography (APT) to analyze these Ni-Si precipitates. The APT results showed two types of diffusion layers at the interface between the Cu matrix and precipitates. The alloy contrast variation method was used to examine the difference in SAXS and SANS intensity in absolute units, which indicated that the δNi2Si precipitates are distorted.