In Situ Reinforced CoCrFeNiTi High-Entropy Alloy Composite Coating: Microstructure, Mechanical Properties, and Wear Resistance

In order to obtain a high-entropy alloy composite coating with high performance, CoCrFeNiTi coatingd and CoCrFeNiTi-B4C coatings were prepared on the surface of AISI 1045 steel by plasma spraying and was remelted by laser technology subsequently. The microstructure, mechanical properties and wear resistance of the two remelted coatings were comparatively studied. The phases of CoCrFeNiTi and CoCrFeNiTi-B4C remelted coating are mainly composed of FCC solid solution structure, but the difference is that the latter has in-situ generated reinforcing phases TiC and eutectic structure (FCC + BCC + (Fe,Cr)2B). Among them, the eutectic structure was cored around in-situ generated (Fe,Cr)2B. Compared with the CoCrFeNiTi remelted coating, the hardness of the CoCrFeNiTi-B4C remelted coating increased from 475 HV0.2 to 747 HV0.2, and the elastic modulus and fracture toughness increased by 6.1 and 119.0%, respectively. Under dry friction condition, the wear rate of the CoCrFeNiTi remelted coating was 5.66 x 10-5 mm3/N m, while that of the CoCrFeNiTi-B4C remelted coating was only 2.28 x 10-6 mm3/N m. The wear mechanism of CoCrFeNiTi remelted coating was mainly abrasive wear, accompanied by adhesive wear and fatigue wear. The wear mechanism of CoCrFeNiTi-B4C remelted coating was mainly fatigue wear, accompanied by slight abrasive wear. Therefore, the CoCrFeNiTi-B4C remelted coating had superior mechanical properties and wear resistance.