Microstructure and mechanical properties of CoCrFeMnNi/WC plasma deposited coating after the spark plasma sintering treatment.

A plasma-deposited CoCrFeMnNi/WC coating was reprocessed by thermoelectric composite treatment via spark plasma sintering (SPS). The microstructure and phase composition of the coating were characterized by a combination of X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The mechanical properties were tested by nanoindentation. After SPS treatment, the coating grains changed from columnar to irregular cellular, and a large amount of carbide precipitates appeared in the ingrain and grain boundary areas, which show an FCC structure that is coherent with the matrix. Through the quantitative calculation of the load–displacement curve, it was found that the hardness of the coating increases from 4.24 GPa to 5.02 GPa, and the yield strength increases from 1069.1 MPa to 1270.4 MPa after SPS treatment. Although the grain size of the coating increased slightly and the dislocation density decreased significantly after SPS treatment, the yield strength of the coating was still significantly improved by precipitation strengthening. • SPS thermoelectric composite treatment caused exsolution precipitation of the coating, resulting in nano-size precipitates. • After SPS treatment, the dislocation density of the coating was greatly reduced while the hardness was improved. • The results of nano-indentation test showed that the yield strength of coating reached 1270.4 MPa after SPS treated. • The effect of precipitation strengthening significantly improves the yield strength of the coating. [ABSTRACT FROM AUTHOR]