A critical review on mechanically alloyed high entropy alloys: processing challenges and properties

Abstract

High entropy alloys (HEAs) earned the attention of the scientific community since their discovery in the year 2004, while the progress in this field has been realized since the year 2010 when a drastic increase in demand for HEAs was observed due to their unique characteristics and ability to form several compositions. As universally acknowledged, the immense potential in compositions, microstructures, and properties has sparked a great interest in this field. Researchers primarily focused on equiatomic HEAs, but the paradigm eventually shifted to non-equiatomic alloys. As the research progressed, four core effects were identified as the most important aspects in enabling the distinct characteristics. Mechanical alloying (MA), followed by the sintering approach, has piqued the interest of all researchers focusing on HEA processing. Accordingly, the main objective of this review is to critically discuss mechanically alloyed HEAs in the view of mechanical properties, tribological behavior, and functional properties. Furthermore, the predominant challenges and their conceivable prospects are also deliberated that offer novelty to this review article.

High entropy materials as emerging electrocatalysts for hydrogen production through low-temperature water electrolysis

“…Typically HEM-based electrocatalysts can be prepared using a variety of methods such as shock decomposition/reduction techniques [78,79], high energy mechano-chemical methods [80] and several conventional wet chemistry methods [81,82]. Details of these methods have been described recently in several publications on HEAs [46,47,50,52,62,67,83] and HEOs [83], to which readers are suggested to refer.…”

“…The strong forces produced by collision and friction between balls and with the container wall generate high energy capable of not only modifying the morphology of materials but also to trigger chemical reactions. As such, ball milling has been widely employed for the synthesis of HEAs [80]. For example, HEAs such as AlCoCrTiZn, AlCoCrFeNi, CoCrFeMnNi, AlFeMnTiCr, AlFeMnTiCo and AlFeMnTiNi were prepared by ball milling (50-60 h at 300-400 rpm) the corresponding metal powder precursors [91,92].…”

Dry sliding wear response of aluminium matrix composites (AMCs): a critical review

“…On the other hand, reinforcing materials used for the development of AMCs are generally hard ceramic particulates (e.g., TiC, SiC, TiB 2 , ZrO 2 ), continuous fibers (e.g., graphite or boron fibers), or discontinuous whiskers [19][20][21][22][23][24][25][26][27]. In addition, mechanically alloyed particles [28][29][30][31], and some agricultural wastes (e.g., rice husk ash, groundnut shell ash, sugarcane bagasse ash,) and industrial wastes (e.g. red mud, fly ash, bottom ash, cenosphere) have also gained attraction as alternatives for the aforementioned traditional reinforcing materials [30,32,33].…”

Synthesis of FeSi–FeAl Composites from Separately Prepared FeSi and FeAl Alloys and Their Structure and Properties

“…During the process, repeated welding, fracturing, and rewelding of powder particles proceeds in the high energy ball mill, together with the severe plastic deformation of the powders. Therefore, the resulting materials have an ultrafine grained structure and improved mechanical properties [24]. Usually, mechanical alloying is considered as a long-term process, but there were several successful attempts to optimize the processing parameters to shorten its duration to tens of minutes or several hours [25].…”