Correlations between microstructural and magnetic properties of a spinodally decomposed Cu52Ni34Fe14 alloy

CuNiFe alloys have shown to be promising materials in terms of manipulating magnetic properties by controlling theirmicrostructure. Despite extensive research activities on such nano-scale magnetic materials for several decades now,the relationship between the evolution of the microstructure and its magnetic properties still remains to be fullyexplored. [1–4]. In this study, we investigate a spinodally decomposed CuNiFe alloy, using a wide variety of modern(S)TEM methods such as dark-field imaging, EDX spectroscopy and differential phase contrast (DPC) imaging. Thespecimen under investigation was solution treated and a subsequent heat treatment at 625°C for 10 hours leads to aspinodal decomposition of the alloy [3,5]. EDX elemental maps reveal the characteristic stripe/plate like Ni-rich phaseembedded in a Cu-rich matrix [1,2]. Those plates are growing along the [100] directions of the crystal which is shownin figure 1 a). The EDX analysis reveals a chemical composition of 54 at% Ni, 27 at% Fe and 19 at% Cu for the Ni-richphase which, is similar to the findings of Kobayashi et al [4]. To investigate the magnetic structure, LM-STEM DPCwith a switched off objective lens was performed to ensure a nearly field-free environment. In DPC, the deflection ofthe electron beam due to the interaction with the magnetic field of the specimen is measured with a 4-quadrantannular detector. A magnetic field map is shown in figure 1 b), in which the colour represents a certain direction of themagnetic field. The DPC map shows a direct relationship between the magnetic field structure and the nanostructurealong the [100] directions. The DPC map displays field vectors that point along the diagonals of the image, suggestinga [111] direction of the magnetic easy axis.