Influence of TiC Content on Wear&Corrosion Resistance of AlCoCrFeNi-Based High-Entropy Alloy Composite Coatings Fabricated by Laser Cladding
TiC-strengthened AlCoCrFeNi-based high-entropy alloy composite coatings were fabricated on the surface of 2255 DSS by laser cladding.The phase composition and micromorphology of AlCoCrFeNi+TiC cladding layers were characterized by X-ray diffractometer and field emission scanning electron micro-scope.The microhardness of the cladding layer was measured by Vickers hardness tester,the wear resis-tance was tested by linear reciprocating friction and wear tester,and the corrosion resistance was tested in an electrochemical workstation.The results show that TiC-strengthened AlCoCrFeNi-based cladding layers mainly consist of BCC phase and TiC phase.As the TiC addition increases,the relative content of TiC phase gradually increases and that of BCC phase gradually decreases.The microstructure of the cladding layer is composed of equiaxed crystal matrix and the second phase,and the matrix grains are gradually refined with the increase of TiC content.With the rising content of TiC,the microhardness of the cladding layer gradu-ally grows due to the dispersion strengthening effect,while the wear resistance first increases and then de-clines.Excessive TiC results in the agglomeration of the second phase and the formation of microstructure defects,which leads to the decrease of the compactness and wear resistance of the cladding layer.The wear mechanism of cladding layers is mainly abrasive wear.As the TiC content rises,the corrosion resistance first increases and then gradually decreases.This is because Ti produced by the dissolution of a small amount of TiC can improve the passivation film formation ability of the cladding layer,while excessive TiC can enhance the galvanic couple corrosion effect.
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