Generalization of intrinsic ductile-to-brittle criteria by Pugh and Pettifor for materials with a cubic crystal structure.

Two classical criteria, by Pugh and Pettifor, have been widely used by metallurgists to predict whether a material will be brittle or ductile. A phenomenological correlation by Pugh between metal brittleness and its shear modulus to bulk modulus ratio was established more than 60 years ago. Nearly four decades later Pettifor conducted a quantum mechanical analysis of bond hybridization in a series of intermetallics and derived a separate ductility criterion based on the difference between two single-crystal elastic constants, C12-C44. In this paper, we discover the link between these two criteria and show that they are identical for materials with cubic crystal structures.

Corrigendum to database on the mechanical properties of high entropy alloys and complex concentrated alloys, data in brief 21 (2018) 2664-2678.

[This corrects the article DOI: 10.1016/j.dib.2018.11.111.].

Comprehensive data compilation on the mechanical properties of refractory high-entropy alloys.

This data article presents the compilation of mechanical properties for 122 refractory high entropy alloys (RHEAs) and refractory complex concentrated alloys (RCCAs) reported in the period from 2010 to the end of January 2018. The data sheet gives alloy composition, type of microstructures and the metallurgical states in which the properties are measured. Data such as the computed alloy mass density, the type of mechanical loadings to which they are subjected and the corresponding macroscopic mechanical properties, such as the yield stress, are made available as a function of the testing temperature. For practical use, the data are tabulated and some are also graphically presented, allowing at a glance to access relevant information for this attractive category of RHEAs and RCCAs.

Microstructural Design for Improving Ductility of An Initially Brittle Refractory High Entropy Alloy.

Typically, refractory high-entropy alloys (RHEAs), comprising a two-phase ordered B2 + BCC microstructure, exhibit extraordinarily high yield strengths, but poor ductility at room temperature, limiting their engineering application. The poor ductility is attributed to the continuous matrix being the ordered B2 phase in these alloys. This paper presents a novel approach to microstructural engineering of RHEAs to form an "inverted" BCC + B2 microstructure with discrete B2 precipitates dispersed within a continuous BCC matrix, resulting in improved room temperature compressive ductility, while maintaining high yield strength at both room and elevated temperature.

Database on the mechanical properties of high entropy alloys and complex concentrated alloys.

This data article presents the compilation of mechanical properties for 370 high entropy alloys (HEAs) and complex concentrated alloys (CCAs) reported in the period from 2004 to 2016. The data sheet includes alloy composition, type of microstructures, density, hardness, type of tests to measure the room temperature mechanical properties, yield strength, elongation, ultimate strength and Young׳s modulus. For 27 refractory HEAs (RHEAs), the yield stress and elongation are given as a function of the testing temperature. The data are stored in a database provided in Supplementary materials, and for practical use they are tabulated in the present paper. The database was used in recent publications by Miracle and Senkov [1], Gorsse et al. [2] and Senkov et al. [3].

Accelerated exploration of multi-principal element alloys with solid solution phases.

Recent multi-principal element, high entropy alloy (HEA) development strategies vastly expand the number of candidate alloy systems, but also pose a new challenge--how to rapidly screen thousands of candidate alloy systems for targeted properties. Here we develop a new approach to rapidly assess structural metals by combining calculated phase diagrams with simple rules based on the phases present, their transformation temperatures and useful microstructures. We evaluate over 130,000 alloy systems, identifying promising compositions for more time-intensive experimental studies. We find the surprising result that solid solution alloys become less likely as the number of alloy elements increases. This contradicts the major premise of HEAs--that increased configurational entropy increases the stability of disordered solid solution phases. As the number of elements increases, the configurational entropy rises slowly while the probability of at least one pair of elements favouring formation of intermetallic compounds increases more rapidly, explaining this apparent contradiction.