Microstructure and properties of in-situ TiN reinforced laser cladding CoCr2FeNiTi high-entropy alloy composite coatings

By Yaxiong Guo, Xiaojuan Shang, Qibin Liu. Surface & Coatings Technology, 2018

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Abstract To prolong the service life of agitator blades in Phosphoric acid reactors, the in-situ TiN particles reinforced CoCr2FeNiTix (x = 0, 0.5, 1) high-entropy alloy (HEA) coatings have been successfully fabricated by laser cladding on 904L stainless steels. The microstructures and phase compositions were analyzed by metallurgical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). The microhardness, wear resistance, and corrosion resistance were measured by microhardness tester, wear and friction machine as well as electrochemical workstation, respectively. The experimental results indicate the phase structures of the coatings are composed of FCC plus TiN and a few Laves phases. The microstructure of the coating is columnar crystal while no Ti elements adding. With the addition of Ti elements, the coating consists of irregular dendritic and granular TiN ceramics as well as a few Laves phases. In the terms of wear resistance, the hardness of the coating containing Ti elements increase significantly. As x = 1, hardness of the coating is more than 3 times higher than substrate, and its wear mass is approximately 1/3 of the substrate. According to the electrochemical polarization curve, the corrosion resistance of the HEA coatings is lower than that of the substrate.

Subfields: Aerospace Engineering, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/8f85c8d735c3c17c5b9dadefb27ac0f71d07a767