Comparison between heat treatment and SPS treatment on CoCrFeMnNi/WC coatings

In this study, spark plasma sintering (SPS) was used for the thermoelectric composite treatment of CrMnFeCoNi/WC plasma transfer arc welding (PTA) coating to explore the difference compared with common heat treatment (HT). X-ray diffraction (XRD) was used to detect the phase composition, and a combination of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) was used to characterize the microstructure. The performance of nano-indentation was tested. The results show that the coating after PTA has a large dislocation density due to internal stress, while HT and SPS treatment significantly reduce the internal stress and dislocation density of the coating. Nano-indentation test shows that the hardness of the coating after PTA is 4.24 GPa, and after HT, the hardness decreases to 4.05 GPa. However, the coating after SPS treatment has significant precipitation-strengthening effect due to the wide existence of the precipitated phase, and the hardness rises to 4.78 GPa.