https://dc.engconfintl.org/cgi/viewcontent.cgi?article=1032&context=superalloys_ii

A critical review of high entropy alloys and related concepts

Microstructures and properties of high-entropy alloys

High-entropy alloys (HEAs) are alloys with five or more principal elements. Due to the distinct design concept, these alloys often exhibit unusual properties. Thus, there has been significant interest in these materials, leading to an emerging yet exciting new field. This paper briefly reviews some critical aspects of HEAs, including core effects, phases and crystal structures, mechanical properties, high-temperature properties, structural stabilities, and corrosion behaviors. Current challenges and important future directions are also pointed out.

https://www.tandfonline.com/doi/pdf/10.1080/21663831.2014.912690

High-Entropy Alloys: A Critical Review

Alloying has long been used to confer desirable properties to materials. Typically, it involves the addition of relatively small amounts of secondary elements to a primary element. For the past decade and a half, however, a new alloying strategy that involves the combination of multiple principal elements in high concentrations to create new materials called high-entropy alloys has been in vogue. The multi-dimensional compositional space that can be tackled with this approach is practically limitless, and only tiny regions have been investigated so far. Nevertheless, a few high-entropy alloys have already been shown to possess exceptional properties, exceeding those of conventional alloys, and other outstanding high-entropy alloys are likely to be discovered in the future. Here, we review recent progress in understanding the salient features of high-entropy alloys. Model alloys whose behaviour has been carefully investigated are highlighted and their fundamental properties and underlying elementary mechanisms discussed. We also address the vast compositional space that remains to be explored and outline fruitful ways to identify regions within this space where high-entropy alloys with potentially interesting properties may be lurking. High-entropy alloys have greatly expanded the compositional space for alloy design. In this Review, the authors discuss model high-entropy alloys with interesting properties, the physical mechanisms responsible for their behaviour and fruitful ways to probe and discover new materials in the vast compositional space that remains to be explored.

High-entropy alloys

https://scholars.cityu.edu.hk/files/27103119/High_entropy_alloy_challenges_and_prospects.pdf

High-entropy alloy: challenges and prospects

The newly enhanced PANDAT, integrating PanEngine, PanOptimizer and PanPrecipitation, bridges thermodynamic calculation, property optimization, and kinetic simulation of multi-component systems based on CALPHAD (CALculation of PHAse Diagram) approach. This software package, in combination with thermodynamic/kinetic/thermo-physical databases, provides an integrated workspace for phase diagram calculation and materials property simulation of multi-component systems. The simulation results, which include thermodynamic, kinetic, thermo-physical properties, and microstructure related information, are critically needed in materials design, in the selection of parameters for fabrication steps such as heat treatment, prediction of performance, and failure analysis. In addition to the functionalities provided by PANDAT as a stand-alone program, its calculation/optimization engines (PanEngine, PanOptimizer and PanPrecipitation) are built as shared libraries and enable their integration with broader applications in the field of Materials Science and Engineering.

http://mcmf.fzu.edu.cn/attach/2014/12/17/57890.pdf

PANDAT software with PanEngine, PanOptimizer and PanPrecipitation for multi-component phase diagram calculation and materials property simulation

PANDAT is a software package for multicomponent phase diagram calculation. Given a set of thermodynamic parameters for all phases in a system and a set of user constraints, PANDAT automatically calculates the stable phase diagram without requiring either prior knowledge of the diagram or special user skills. The features of PANDAT are discussed and some application examples presented. In addition to PANDAT, its calculation engine, PanEngine, is also discussed.

The PANDAT software package and its applications

The concept of High Entropy Alloy (HEA) is understood from the point of view of phase diagram calculation. The role of entropy of mixing on the phase stability is discussed for both ideal and non-ideal solid solution phases. The relative stability of a solid solution phase and line compounds is illustrated using hypothetical systems. Calculated binary and multicomponent phase diagrams are used to explain the phenomena observed experimentally for HEAs. The potential of using the CALPHAD (CALculation of PHAse Diagrams) approach in aiding the design of alloys with multiple key components is also discussed.

An understanding of high entropy alloys from phase diagram calculations

Thermodynamic calculation is used to shed light on the design and development of high-entropy alloys (HEAs) in this article. A thermodynamic database for the Al-Co-Cr-Fe-Ni was developed, and phase diagrams of this system were calculated. The calculated results, such as primary solidified phases, which are fractions of stable phases at a given alloy composition, explain the published experimental observations fairly well for both as-cast and homogenized alloys. These calculations also confirm the effect of each element on the face-centered cubic (fcc)/body-centered cubic (bcc) structure transition as published in the literature. The role of thermodynamic calculation in aiding effective design of HEAs is clearly demonstrated by this work.

Shuanglin Chen

Papers

PANDAT software with PanEngine, PanOptimizer and PanPrecipitation for multi-component phase diagram calculation and materials property simulation

The PANDAT software package and its applications

An understanding of high entropy alloys from phase diagram calculations

Computational Thermodynamics Aided High-Entropy Alloy Design

Phase diagram calculation: past, present and future