Microstructure and nanoindentation creep behavior of CoCrFeMnNi high-entropy alloy fabricated by selective laser melting

Selective laser melting (SLM) was used to fabricate an equiatomic CoCrFeMnNi high-entropy alloy (HEA). The SLM-fabricated CoCrFeMnNi HEA samples were studied with X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), electron backscatter diffraction (EBSD) and nanoindentation techniques to characterize the microstructure and creep behavior. It was found that the HEA comprised a single face-centered cubic (fcc) structure. Due to the fast solidification and high temperature gradients of the molten pool during the SLM process, the microstructure comprised cellular subgrains with grain boundary angles lower than 5 degrees. Based on energy dispersive spectrometry (EDS) maps, the constituent elements of the SLM-fabricated HEA were homogenously distributed. Moreover, the effect of the peak holding load on the nanoindentation creep deformation of the SLM-fabricated HEA was investigated using a Berkovich indenter. The results of this study indicated that the creep was mainly dominated by deformation controlled by dislocation motion.