ABSTRACT
Alloys with superior properties represent the main topic of recent studies due to their effectiveness in reducing the cost of equipment maintenance and enhancing usage time, in addition to other benefits in domains such as geothermal, marine, and airspace. Al0.5CrFeNiTi was produced by solid state processing in a planetary ball mill, with the objective of obtaining a high alloying degree and a homogenous composition that could be further processed by pressing and sintering. The metallic powder was technologically characterized, indicating a particle size reduction following mechanical alloying processing when compared to the elemental raw powder materials. The microstructural analysis presented the evolution of the alloying degree during milling but also a compact structure with no major defects in the pressed and sintered bulk samples. The X-ray diffraction results confirmed the presence of face-centered cubic (FCC) and body-centered cubic (BCC) phases, predicted by the theoretical calculations, along with a hexagonal close-packed (HCP) phase, where the Al, Cr, Fe, Ni, and Ti phase was identified in both the alloyed powder material and sintered sample.
ABSTRACT
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.
