The Surface Properties of Implant Materials by Deposition of High-Entropy Alloys (HEAs)

Abstract

High-entropy alloys (HEAs) contain more than five alloying elements in a composition range of 5–35% and with slight atomic size variation. Recent narrative studies on HEA thin films and their synthesis through deposition techniques such as sputtering have highlighted the need for determining the corrosion behaviors of such alloys used as biomaterials, for example, in implants. Coatings composed of biocompatible elements such as titanium, cobalt, chrome, nickel, and molybdenum at the nominal composition of Co30Cr20Ni20Mo20Ti10 were synthesized by means of high-vacuum radiofrequency magnetron (HVRF) sputtering. In scanning electron microscopy (SEM) analysis, the coating samples deposited with higher ion densities were thicker than those deposited with lower ion densities (thin films). The X-ray diffraction (XRD) results of the thin films heat treated at higher temperatures, i.e., 600 and 800 °C, revealed a low degree of crystallinity. In thicker coatings and samples without heat treatment, the XRD peaks were amorphous. The samples coated at lower ion densities, i.e., 20 µAcm−2, and not subjected to heat treatment yielded superior results in terms of corrosion and biocompatibility among all the samples. Heat treatment at higher temperatures led to alloy oxidation, thus compromising the corrosion property of the deposited coatings.

Comparative in-vitro microscopic evaluation of vertical marginal discrepancy, microhardness, and surface roughness of nickel–chromium in new and recast alloy

“…Therefore, recast alloy can be utilized in fixed prosthodontics with respect to microhardness. Usman et al 36 conducted similar research, concluding that the marginal fitness of the new alloy was superior to that of the recast alloy. Usman claimed that the marginal gap between recast and fresh alloys is caused by oxidization, vaporization, and porosity.…”

Synthesis of High-Entropy Alloys with a Tailored Composition and Phase Structure Using a Single Configurable Target

“…The discovery of high-entropy alloys (HEAs) by Yeh et al has promoted the development of new concepts and fresh perspectives on alloy design within the emerging era of HEAs. − HEAs consist of five or more principal elements with equal or nearly equal atomic ratios and form single-phase solid solutions. The concentration of each element in HEA typically lies in the range of 5–35 atom %; , however, some HEAs may also contain minor elements with concentrations below 5 atom % . In equimolar HEAs, each element has an equal probability of occupying lattice sites in the crystal structure .…”