Analytical electron tomography of CuNiFe magnetic spinodal alloys

Many properties and effects connected to the microstructure of materials are being redefined andexpanded with the development of 3D characterization techniques. In this manner, magneticspinodal alloys of copper-nickel-iron have already proven themselves a valuable material forapplications ranging from electric motors to data storage and spintronics. Despite their longinvestigation history and the consistent reports of variations in microstructure having influence onmechanical and magnetic properties [1,2], the whole picture is still not understood. The exactrelationship between the microstructural anisotropy and material performance remains an activefield of research.Analytical techniques play important role in visualization and quantification of the chemicalcomposition and morphology of the alloy constituents. Electron energy loss spectroscopy (EELS)and energy-dispersive X-ray spectroscopy (EDXS) were used to define the precipitates inCu75Ni20Fe5 alloys [3]. 3D study using high-angle annular dark field (HAADF) STEM tomographyand 3D data analysis tools were shown effective and insightful for high entropy alloys [4] and,combined with analytical tools, were used to describe the complex phases of alnico alloys [5].In this study we incorporate EDXS and EELS measurements in the process of HAADF tilt seriesacquisition (Figure 1) to create three complementary 3D representations of Cu52Ni34Fe14 alloysample. Samples are prepared with focused ion beam as 200-300 nm thick pillars to allow full180° tomography acquisition angle. Elemental mapping in 3D is used to analyse chemicalcomposition of Cu and Ni+Fe rich platelet-like phases and quantify the spinodal wavelengths inthree dimensions. Explored are also the ligament interconnectivity and relationship betweenstructure anisotropy and magnetic properties.