The XRD pattern of the (CoCrFeNi)95Nb5 HEA powder is shown in Figure 1a. As can be seen, only diffraction peak of simple FCC phase is found on the pattern, indicating no precipitation of second phase. This result is significantly different from the as-cast CoCrFeNiNbx HEAs with similar composition, where the ordered Laves phase with hexagonal close-packed (HCP) structure could form in FCC matrix with additions of a small amount of Nb. Obviously, during the preparation process, the second phase is inhibited and the supersaturated solid solution structure in high temperature state is retained to room temperature during atomization process.
Figure 1. X-ray diffractometer (XRD) patterns of (CoCrFeNi)95Nb5 high-entropy alloy (HEA) powder (a) and coating (b).
The SEM image of (CoCrFeNi)95Nb5 HEA powder is shown in Figure 2a. It can be seen that the powder is nearly spherical, and the diameter of the particles is from 10 _m to 30 _m. As seen from Figure 2b, the surface of the spherical powder is not smooth, distributing inhomogeneously as a grid. The EDS results (Table 1) and mappings (Figure 2c–g) of HEA powder indicate that composite of powder is very close to the designed nominal composition and the distribution of each element in the single powder is highly uniform.
Figure 2. (a,b) Scanning electron microscope (SEM) images of the (CoCrFeNi)95Nb5 HEA powder, (c–g) Chemical analysis of HEA powder by energy dispersive spectrometry (EDS).
Table 1. Nominal compositions and chemical compositions of (CoCrFeNi)95Nb5 HEA powder and coating (at.%)
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