Analysis of the decomposition of Cu–Ni and Fe–Ni alloys at lower temperatures by atom probe

The decomposition of alloys can lead to concentration fluctuations with small amplitude and spatial extension. A technique of data evaluation, the repeated smoothing procedure (RSP), is described by which atom probe data of such alloys can be analysed. The procedure is applied to a Fe–Ni Invar alloy, annealed at 625°C, and to two Cu–Ni alloys, annealed at 300°C and at 350°C. Decomposition was observed and quantified in both alloy systems.