High entropy alloys (HEAs) are being attracted recently by several researchers, scientists, and academicians to achieve extraordinary and outstanding properties that cannot be obtained from conventional alloys. HEAs are multicomponent alloys in which a minimum of five metallic elements are mixed in an equal molar or non-equal molar ratio. The rapid growth of this field produces a huge amount of scientific papers over the last decade. However, still, there is a need to review various manufacturing methods and their results. Also, the outcome of the scientific articles related to HEAs has ignored the various methods of synthesizing and manufacturing. In this review article, an attempt was made and largely concentrated on the methods and techniques that can be used in the manufacturing and synthesizing of the HEAs. Recently, the properties of HEAs become much better when compared to conventional alloys. Some techniques have succeeded in producing ultrafine microstructure grains which become a leap in industrial fields. Now, the manufacturing methods of conventional alloys are almost familiar and implemented according to the suggestions given by the researchers and academicians based on their work. Therefore, the present review article has demonstrated various methods of manufacturing of HEAs with novel schematics with a preview description for more understanding of the basic work criteria. Besides, this article has reviewed the outcomes of several research articles related to several methods, then compared the outcome of each method with the corresponding mechanical properties, and major challenges of HEAs are discussed and reported.

Abstract:During the past few decades, ultrafine-grained materials (UFG) have experienced rapid development. Enhanced mechanical and surface properties, such as strength, ductility and erosioncorrosion (E-C) resistance by refining the grain to ultra-fine/nanometer size has been achieved. The equal channel angular pressing (ECAP) is a popular severe plastic deformation (SPD) method to fabricate UFG bulk materials. In this research, the E-C behavior of commercial annealed pure copper subject to four passes of ECAP have been investigated. Hardness measurement of the copper specimen after four passes of ECAP showed an increase of 200% on the hardness value as compared with annealed condition. Simulated seawater was used as an E-C medium. The effect of different E-C parameters such as time, slurry flow velocity, impact angle, and solid particle concentration on ECAP process is studied. The results showed that ECAP enhances the E-C resistance of copper, and this behavior improves with increasing the pass number. Generally, a 30% rise in resistance to E-C was achieved after four ECAP passes as compared to coarse grain copper for the parameters studied in this work. Optical microscopy was used to examine the microstructure and material removal mechanism of the annealed copper. Scanning electron microscopy (SEM) was used to validate the reduction of grain size due to ECAP process. Furthermore, examination of the surface roughness of the copper at different ECAP passes showed that for the same E-C condition the increment of ECAP passes leads to a smoother surface.

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