Effect of Element W on Microstructure and Properties of High-entropy Alloy Ni₆Cr₄W_xFe₉Ti Laser Cladding Coatings

The introduction of refractory metal W into multi-principal alloy matrices is an effective way to refine microstructure and enhance mechanical and corrosion-resistant properties. In this work, Ni₆Cr₄W_xFe₉Ti (x= 0, 0.5, 1.0, 1.5) high-entropy alloy (HEA) cladding coating is prepared by mechanical alloying and laser melting deposition. Based on clarifying the formation mechanism of the HEAs, the influences of W atomic ratio on the cladding microstructure, and mechanical and corrosion resistance properties are investigated. The results indicate that the Ni₆Cr₄W_xFe₉Ti powders mechanically alloyed for 4 h are primarily composed of dual-phase structure of FCC and BCC. After laser melting deposition, the dual-phase structure is transformed into a single-phase FCC structure. With the increasing of W atomic ratio, the grain size of the cladding coating gradually decreases. The grain size of Ni₆Cr₄W_1.5Fe₉Ti cladding layer is the smallest, about 3-5 μm and its hardness and compressive strength reach 456 HV and 1 376 MPa, respectively. The self-corrosion current density of Ni₆Cr₄W_1.5Fe₉Ti alloy decreases by three orders of magnitude compared compared to the W-free Ni₆Cr₄Fe₉Ti alloy. This research provides reference for the preparation of alloys with complicate compositions and the corrosion resistamce is improved.