Nanostructured AlNiCoFeCrTi high-entropy coating performed by cold spray

Abstract

In this work, solid-state mechanical alloying (MA) and cold spraying (CS) processes were applied to fabricate powder AlNiCoFeCrTi high-entropy alloy (HEA) and then to produce HE coatings on steel substrate. Shot-time MA for 3 h has been employed to synthesize nanostructured equiatomic AlNiCoFeCrTi HEA of metastable supersaturated substitutional solid solution with bcc crystal structure. Although alloying is not complete at this shot milling time, it goes to completion during thermal annealing to achieve the alloy formation. XRD study on mechanically alloyed high-entropy AlNiCoFeCrTi alloy after thermal annealing at 1200 °C for 1 h revealed the formation of a three-phase structure consisting of ordered bcc phase with fine precipitates of intermetallic σ-phase (FeCr) and titanium carbide TiC. The powder agglomerates resulted from annealing were grinded in a ball mill for 1 h. Nanostructured disordered bcc solid solution, TiC and σ-phases are noticed after milling. Coatings of 450 μm in mean thickness were deposited by the CS process using an air like a working gas, temperature and pressure of 450 °C and 0.9 MPa, respectively. The experimental results confirm that CS process can be used to produce HE coatings with low porosity. As a low-temperature deposition process, CS completely retained the HEA phase composition and nanostructure in the coating without any phase transformation. The AlFeNiCoCrTi HE coatings exhibit 10.3 ± 0.3 GPa in Vickers hardness.

High Entropy Alloy Coatings and Technology

“…Hushchyk et al cold sprayed AlNiCoFeCrTi HEA milled powder on the steel substrate. Their results confirmed that HEA coatings were produced with low porosity as a low-temperature process and there was no phase composition change in HEA coating without any phase transformation [76]. The AlNiCoFeCrTi HEA coatings were highly dense and vary from 430-470 µm in thickness.…”

“…By using various sources of energy, such as thermal, electrical, or mechanical energy to achieve fine-grained [71,[88][89][90]. Various authors have used mechanically alloyed HEA powder for plasma spraying on a harder substrate [76,91]. Tian et al ball-milled AlCoCrFeNiSi HEA powder for 10 h to obtain BCC and FCC dual-phase HEA alloy which was further plasma sprayed on 316 stainless steel substrates.…”

Cold Spray Coatings of Complex Concentrated Alloys: Critical Assessment of Milestones, Challenges, and Opportunities

“…Web of Science 2019 Deposition of FeCoNiCrMn high entropy alloy (HEA) coating via cold spraying [200] First report on cold-sprayed AlCoCrFeNi high-entropy alloy and its isothermal oxidation [269] 2020 Cold Gas Spraying of a High-Entropy CrFeNiMn Equiatomic Alloy [207] Nanostructured AlNiCoFeCrTi high-entropy coating performed by cold spray [270] Table 9. Cont.…”

Tribological Performance of High-Entropy Coatings (HECs): A Review

“…Currently, most authors have developed HECs by using different coating methods such as magnetron sputtering [ 95 , 96 , 97 ], laser cladding [ 98 , 99 ], induction cladding [ 100 ], plasma spraying [ 54 , 69 , 70 , 97 ], electrodeposition [ 101 ], high velocity oxy-fuel (HVOF) [ 41 , 50 , 51 , 54 , 55 , 56 , 59 , 61 , 65 ], cold spraying [ 102 , 103 , 104 , 105 ] and many others. Moreover, numerous methods are available to prepare the powder before cladding/spraying to get into a uniform size and shape, including atomization, mechanical alloying, and ball milling.…”