Influence of Specific Energy on Microstructure and Properties of Laser Cladded FeCoCrNi High Entropy Alloy

Abstract

Specific energy is a key process parameter during laser cladding of high entropy alloy (HEA); however, the effect of specific energy on the microstructure, hardness, and wear resistance of HEA coating has not been completely understood in the literature. This paper aims at revealing the influence of specific energy on the microstructure and properties of laser cladded FeCoCrNi high entropy alloy on the Ti6Al4V substrate, and further obtains feasible process parameters for preparation of HEA coating. Results indicate that there are significant differences in the microstructure and properties of the coatings under different specific energy. The increase of specific energy plays a positive role in coarsening the microstructure, promoting the diffusion of Ti from the substrate to HEA coating, and subsequently affects the hardness of samples. The HEA coating is mainly composed of the face-centered cubic phase and body-centered cubic phase, precipitating a small amount of Fe-Cr phase and Laves phase. Metallurgical bonding is obtained between the base metal and the coatings of which the bonding region is mainly composed of columnar crystal and shrinkage cavities. The microhardness of the HEA coating reaches 1098 HV, which is about 200% higher than that of the TC4 substrate, and the wear resistance is significantly improved by the HEA coating.

Microstructure and Wear Resistance of Laser Cladding of Fe-Based Alloy Coatings in Different Areas of Cladding Layer

“…In the heat-affected zone, the liquid metal rapidly solidifies, and base remelting occurs. The mixing degrees of the cladding material and the base material are different, resulting in an alloy composition representing the difference between them; the grains are coarse, and the microhardness is significantly reduced [ 14 ].…”

“…The ability to resist plastic deformation is enhanced, and plastic deformation becomes difficult, which makes this region high in hardness. an alloy composition representing the difference between them; the grains are coarse, and the microhardness is significantly reduced [14]. It can be observed from the figure that the average hardness value of the middle region of Sample A is 476.6 HV0.3, which is larger than the average hardness value of the upper region, and the hardness value of the upper region of Sample B is 500.1 HV0.3, which reaches the maximum.…”

A Review on the Tribological Performances of High‐Entropy Alloys

“…Wang et al have focused on the effect of specific energy on microstructure and wear behavior of FeCoCrNi HEA coating. [ 131 ] Figure a is the schematic diagram of the experimental setup of laser cladding. The results showed that the coating gradually translated from a mixture phase of FCC and BCC to the BCC phase, accompanied by small amount of Laves phase and Fe–Cr phase with the increasing of specific energy, as shown in Figure 28b.…”

Microstructures, Corrosion Resistance and Wear Resistance of High-Entropy Alloys Coatings with Various Compositions Prepared by Laser Cladding: A Review

“…Due to the element content of HEA being much higher than that of traditional engineering alloys, block HEAs have not been applied on a large scale in the industrial field due to cost constraints. As a coating material, HEAs not only offer advantages of excellent corrosion resistance [22][23][24], wear resistance [25,26], and oxidation resistance [27], but also overcome the disadvantages of high engineering application costs, which is the primary direction of the development of HEAs. In addition, HEAs have certain requirements for the cooling speed and undercooling degree in the preparation process, and the coating has the characteristics of fast cooling due to the small forming scale, which can effectively inhibit the generation of intermetallic compounds during the forming [28][29][30][31][32].…”