Combined Atom Probe Tomography and TEM Investigations of CoCrFeNi, CoCrFeNi-Pd_x (x=0.5, 1.0, 1.5) and CoCrFeNi-Sn

The structure of a family of high entropy alloys based on the composition CoCrFeNi, to which Pd and Sn have been added, is presented. The results stem from combined investigations by atom probe tomography as well as by scanning and transmission electron microscopy on samples produced by arc melting. Although CoCrFeNi is of fcc structure, the sample is not homogeneous on atomic scale. The addition of Pd as a fifth element retains the fcc lattice with the indication of the coexistence of at least two additional phases. The addition of Sn changes the general structure considerably.