Study On Microstructure And Properties Of FeCoNiCrMo-WC/TiC High Entropy Alloy Laser Cladding Layer

Laser cladding is a key technology in the field of intelligent remanufacturing and has broad development prospects.However,the problem of few types of cladding materials is an important reason for restricting the wide application of laser cladding technology.High entropy alloy has excellent comprehensive properties and is expected to be used as laser cladding material,but its wear resistance needs to be improved.At present,improving the wear resistance of the alloy by adding ceramic particles WC and TiC is a research hotspot in the field of surface engineering.In this paper,FeCoNiCrMo high-entropy alloy is taken as the research object,and the reasonable laser power range for preparing FeCoNiCrMo high-entropy alloy cladding layer is studied.Under the optimal laser power,FeCoNiCrMo-x WC（x=0,5,10,15wt%）and FeCoNiCrMo-x TiC（x=0,5,10,15wt%）high-entropy alloy cladding layers are prepared.The effects of WC and TiC addition on the microhardness,microstructure,phase structure,friction properties and corrosion resistance of the cladding layer were studied.The main results are as follows:When the laser power is lower than 1.6 k W,the FeCoNiCrMo cladding layer prepared by laser cladding is FCC phase structure,the solidification structure is relatively coarse,and the comprehensive performance is poor.When the laser power is 1.6～2.0 k W,the cladding layer is metallurgically bonded to the substrate,and the cladding layer is composed of FCC and BCC phases.The higher laser power is beneficial to promote the formation of BCC phase,which can significantly improve the wear resistance and corrosion resistance of the cladding layer.When the laser power is 1.8 k W,the wear resistance and corrosion resistance of the cladding layer are the best,the wear rate is 0.71×10^-5g·N^-1·m^-1,and the self-corrosion current density is 1.69×10^-9A/cm².Excessive laser power will increase the residual stress and crack sensitivity of the cladding layer,reduce the surface quality of the cladding layer,and lead to a decrease in the comprehensive performance of the cladding layer.After adding ceramic particle WC,the cladding layer is composed of FCC and BCC phases,containing a small amount of WC,W₂C and Cr₇C₃phases,and the microstructure is columnar crystal and cellular crystal.When the WC content is between 0wt%and 15wt%,with the increase of WC content,the content of WC,W₂C,Cr₇C₃and BCC phase increases,and the grain size is refined.When the WC content is 10wt%,the wear resistance of the cladding layer is the best,the wear rate is 4.21×10^-6g?N^-1?m^-1,and the wear rate is about40.7%lower than that of the cladding layer without WC.The corrosion current density of15wt%WC cladding layer is relatively small,which is 2.09×10^-8A/cm²,only 1.4%of the corrosion current density of 42Cr Mo matrix.After adding ceramic particles TiC,the cladding layer is mainly composed of FCC and BCC phases,containing a small amount of TiC,Cr₂₃C₆and Cr_1.39Ti_1.07phases,and the microstructure is equiaxed crystal and columnar crystal.When the TiC content is between 0～15wt%,with the increase of TiC content,the content of TiC,Cr₂₃C₆,Cr_1.39Ti_1.07and BCC phase increases,and the microstructure grain is refined.When the TiC content is 5wt%,the wear resistance of the cladding layer is the best,and the wear rate is 3.41×10^-6g?N^-1?m^-1,which is about 55.7%lower than that before adding TiC.The corrosion current density of the cladding layer with 10wt%TiC content is relatively low,which is 2.16×10^-8A/cm²,which is only 1.5%of the corrosion current density of the substrate 42CrMo.