For the past decade and a half, high entropy alloys have drawn great research interest in both materials science and engineering society. Unlike conventional alloys, which normally contain one or two major elements, high entropy alloys comprise multiple principal elements in high concentrations. The multi-dimensional composition space from this alloying strategy can greatly expand the alloy design range and offer new possibilities for improving material performance. The multiprincipal-element character of high entropy alloys leads to four important core effects, including high entropy effect, sluggish diffusion effect, severe-lattice-distortion effect and cocktail effect. The core effects provide novel properties to high entropy alloys, such as excellent specific strength, superior mechanical performance at high temperatures, exceptional ductility and fracture toughness at cryogenic temperatures, superconductivity and excellent radiation resistance. Therefore, high entropy alloys have good potential application prospects in coating materials, low-temperature structural materials, thermoelectric materials, superconducting materials, aerospace materials and nuclear materials. Furthermore, the concept of “high entropy” has now extended from alloys to other functional materials. Recent studies have reported that some high entropy materials possess excellent catalytic and hydrogen-absorbing properties, greatly expanding the application areas of high entropy materials.

One topic of this special issue is about the preliminary researches of high entropy materials. It consists of six review papers from researchers in various countries including China, Sweden, and Australia. Prof. Yi-Ping Lu reviews the manufacturing and service performance of tungsten-containing high entropy alloys. Dr. Hua-Hai Shen presents the preliminary assessment of high entropy alloys for tritium storage. Dr. Tan Shi reviews the current development of body-centered cubic high entropy alloys, especially refractory high entropy alloys, on its potential use in both fission and fusion reactors. Dr. He Huang specifically focused his review on W-based high entropy alloys that are considered as candidate materials in nuclear fusion. In addition to high entropy metals, an interesting perspective review about high entropy carbide ceramics has been reported by Prof. Zheng-Gang Wu. Dr. Wen-Yi Huo presents recent progress on high entropy materials used as high-performance catalysts for electrocatalytic water splitting applications.

Interestingly, four of the papers above specifically studied or at least discussed the potential of high entropy alloys for nuclear applications, indicating the urgent needs to develop advanced materials for new-generation nuclear energy. Following this demand, this special topic issue also includes two articles on W-based nuclear materials used in fusion reactors. Dr. Wei Liu reviews the recent progress of the laser powder bed fusion fabrication of tungsten, which is a type of additive manufacturing technology that can easily fabricate complex parts used in fusion reactors. A research article from Prof. Qing Peng investigates the defect evolution in tungsten by molecular dynamics method.

We hope this issue will provide a good inspiration for researchers, scientists and graduate students who have interest in high entropy materials, leading more researchers to explore this limitless and promising field.

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Dr. Chen-Yang Lu

Dr. Yi-Ping Lu

May 01, 2021