“…In order to establish the final sintering parameters for the magnetron sputtering targets, in correlation with other experimentations from the literature [20,21] and adjusted for the present research, several tests were carried out by varying the sintering temperature from 800 • C to 975 • C, with the other parameters remaining constant: a pressure of 50 MPa, a heating/cooling rate of 50 • C/min and a dwell time of 5 min.…”
The main objective of this study was to develop a high-entropy alloy (HEA) derived from the CoxCrFeNiTi HEA system (x = 0.5, 1) for protective coatings using the magnetron sputtering method. In order to produce the high-entropy alloy targets required for the magnetron sputtering process, mechanically alloyed metallic powders were consolidated via spark plasma sintering (SPS). The microstructural analysis results of the HEA mixture presented morphology changes after 30 h of alloying, with the particles presenting uniform polygonal shapes and dimensions. Subsequently, 316L stainless steel (SS) specimens were coated via magnetron sputtering, comparing their composition with that of the sputtering targets used for deposition to establish stoichiometry. Microstructural analyses of the SPSed HEAs revealed no defects and indicated a uniform elemental distribution across the surface. Furthermore, the CoCrFeNiTi equiatomic alloy exhibited a nearly stoichiometric composition, both in the coating and the sputtering target. The XRD analysis results indicated that amorphous coatings were obtained for both Co0.5CrFeNiTi and the CoCrFeNiTi HEA, and nanoindentation tests indicated that the CoCrFeNiTi HEA coating presented a hardness of 596 ± 22 HV, compared to the 570 ± 19 HV measured for Co0.5CrFeNiTi, suggesting an improved wear resistance.
“…In order to establish the final sintering parameters for the magnetron sputtering targets, in correlation with other experimentations from the literature [20,21] and adjusted for the present research, several tests were carried out by varying the sintering temperature from 800 • C to 975 • C, with the other parameters remaining constant: a pressure of 50 MPa, a heating/cooling rate of 50 • C/min and a dwell time of 5 min.…”
The main objective of this study was to develop a high-entropy alloy (HEA) derived from the CoxCrFeNiTi HEA system (x = 0.5, 1) for protective coatings using the magnetron sputtering method. In order to produce the high-entropy alloy targets required for the magnetron sputtering process, mechanically alloyed metallic powders were consolidated via spark plasma sintering (SPS). The microstructural analysis results of the HEA mixture presented morphology changes after 30 h of alloying, with the particles presenting uniform polygonal shapes and dimensions. Subsequently, 316L stainless steel (SS) specimens were coated via magnetron sputtering, comparing their composition with that of the sputtering targets used for deposition to establish stoichiometry. Microstructural analyses of the SPSed HEAs revealed no defects and indicated a uniform elemental distribution across the surface. Furthermore, the CoCrFeNiTi equiatomic alloy exhibited a nearly stoichiometric composition, both in the coating and the sputtering target. The XRD analysis results indicated that amorphous coatings were obtained for both Co0.5CrFeNiTi and the CoCrFeNiTi HEA, and nanoindentation tests indicated that the CoCrFeNiTi HEA coating presented a hardness of 596 ± 22 HV, compared to the 570 ± 19 HV measured for Co0.5CrFeNiTi, suggesting an improved wear resistance.
“…Beyond MA and atomising to produce fully prealloyed HEA powders, another innovative approach was developed in [8], where by means of a heat treatment, a core-shell powder with a TiN layer on the surface is obtained, with the core being a CoCrNiFe HEA obtained by MA. The base powder was heat treated in a N 2 +Ar atmosphere with the gas flow rate fixed at 1 l/ min to optimise the efficiency of the coating.…”
Section: Powder Development and Processingmentioning
confidence: 99%
“… Figure 3 Schematic representation of core–shell powder formation. After [8]. Figure 4 SEM/EDS imaging of the heat treated powder microstructure at P N2 / P Ar ratios of (a) 1.00, (b) 0.67, (c) 0.33 and (d) 0.10.…”
Section: Powder Development and Processingmentioning
confidence: 99%
“… Figure 4 SEM/EDS imaging of the heat treated powder microstructure at P N2 / P Ar ratios of (a) 1.00, (b) 0.67, (c) 0.33 and (d) 0.10. After [8]. …”
Section: Powder Development and Processingmentioning
This article addresses the development of high-entropy alloys (HEAs) fabricated via Powder Metallurgy (PM) techniques. There are potential opportunities for PM techniques to produce 'different' HEAs and offer alternative routes to obtain special compositions. The potential for PM is vast, and the obtained properties are highly competitive with those from HEAs produced by ingot casting. Considerable work must still be done to provide the market with reasons to use PM instead of other processing routes. Since article [Torralba JM, Alvaredo P, García-Junceda A. High-entropy alloys fabricated via powder metallurgy. A critical review.
“…This unique powder structure allows a convenient superimposition of the core and shell phase properties [5,6]. Owing to their high functionality, core-shell structured powders have been developed for a wide range of applications including magnets [7][8][9][10][11], semiconductors [12], organic/inorganic composites [13,14], and metal matrix composites [5,15]. These specialized materials have allowed the researchers to go beyond the property limits of traditional single phase materials [5].…”
Core-shell structured magnetic nanoparticles combine hard and a soft phases to improve energy efficiency. The mutual interaction of the two phases can lead to the exchange spring effect leading to higher magnetic energy. In this regard, synthesis of Nd2Fe14B based core-shell structured powders have proven to be elusive due to the relatively reactive nature of this phase. In this study, a process has been established for successfully coating the surface of Nd2Fe14B powders with FeCo layer using galvanic displacement method. Initially, a binary phase magnetic powder was synthesized containing Nd2Fe14B and Nd2Fe17 phase. Subsequently, the powders were coated using a Co precursor at 303 K. During coating the metastable Nd2Fe17 phase was dissolved and the Fe ions were released into the solution. Subsequently, the Fe ions deposited together with the Co ions on the surface of Nd2Fe14B powder to form a FeCo shell. The deposited layer thickness and composition was confirmed using TEM analysis.
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