Nanostructured AlNiCoFeCrTi high entropy coating performed by cold spray

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

"Materials science of refractory compounds" (MSRC-2021), 7th International Samsonov conference

These study is aimed at developing oxidation-resistant HEA coating by solid-state cold spray (CS) process for potential applications at high operating temperatures. The CS AlNiCoFeCrTi coating oxidized to form a thin alumina layer, thereby successfully protecting the underlying substrate from oxidation at 900 °C for 100 h continuously

"Materials science of refractory compounds" (MSRC-2021), 7th International Samsonov conference

In this paper, solid-state mechanical alloying (MA) and cold spray (CS) processes were applied to produce AlNiСоFeCrTi high-entropy alloy (HEA) powder and then to produce HE coatings on steel substrate. Shot-time MA for 3 h has been employed to synthesize nanocrystalline equiatomic Al-NiCoFeCrTi HEA powder of metastable supersaturated substitutional solid solution with bcc crystal structure. Deposition of powdered AlFeNiCoCrTi HEA was performed by CS process on a steel substrate using an air with a gun temperature and pressure of 450 °C and 0.7 MPa, respectively. Coatings with thickness about 300 mkm were obtained. The coat-ings were dense, relatively uniform, and adherent (no interfacial cracks or debonds)

Phase-structural state of the high-entropy of AlcoNiFeCrTi alloy in the process of mechanical alloying and homogenization

Представлено результати синтезу високоентропійного AlCoNiFeCrTi сплаву з елементарної порошкової суміші методом короткочасного механічного легування (МЛ) в високоенергетичному планетарному млині та наступного відпалу при температурі 1200 °С протягом 1 години. Методами рентгеноструктурного та мікроструктурного аналізу досліджено фазові та структурні перетворення під час МЛ та після відпалу сплавів. Синтезовані високоентропійні AlCoNiFeCrTi сплави залежно від часу МЛ складаються з ОЦК та ГЦК твердих розчинів, інтерметалідних сполук AlTiСо2, Cr0,99Fe1,01 (σ-фаза) та карбіду титану ТіС. Мікротвердість HV сплавів після відпалу становить 9-10 ГПа.The results of the synthesis high entropy AlCoNiFeCrTi alloy from elemental powder mixture by short-term mechanical alloying (MA) method in high energy planetary mill and subsequent annealing at 1200 С for 1 hour were shown. Phase and structural transformations were studied by X-ray diffraction and microstructural analysis with MA and after annealing alloys. Synthesized high entropy AlCoNiFeCrTi alloys consist of BCC and FCC solid solutions, intermetallic compounds AlTiÑî2, Cr0,99Fe1,01 (σ-phase) and TiC depending on time MA. The microhardness of HV alloys after annealing is 9–10 GPa.Представлены результаты синтеза високоентропийного AlCoNiFeCrTi сплава с элементарной порошковой смеси методом кратковременного механического легирования (МЛ) в высокоэнергетическом планетарном мельнице и последующего отжига при температуре 1200 °С в течение 1 часа. Методами рентгеноструктурного и микроструктурного анализа исследованы фазовые и структурные превращения в процессе МЛ и после отжига сплавов. Синтезированные високоентропийные AlCoNiFeCrTi сплавы в зависимости от времени МЛ состоят из ОЦК и ГЦК твердых растворов, интерметаллидных соединений AlTiСо2, Cr0,99Fe1,01 (σ-фаза) и карбида титана ТiС. Микротвердость HV сплавов после отжига составляет 9-10 ГПа