https://zenodo.org/record/1258680/files/article.pdf

The influences of temperature and microstructure on the tensile properties of a CoCrFeMnNi high-entropy alloy

Tensile properties of high- and medium-entropy alloys

Influence of phase transformations on the mechanical properties of austenitic stainless steels

The term " high-entropy alloys (HEAs) " first appeared about 10 years ago defining alloys composed of n = 5 - 13 principal elements with concentrations of approxi- mately 100/ n at.% each. Since then many equiatomic (or near equiatomic) single- and multi-phase multicomponent alloys were developed, which are reported for a combina- tion of tunable properties: high hardness, strength and ductility, oxidation and wear resistance, magnetism, etc. In our paper, we focus on probably single-phase HEAs (solid solutions) out of all HEAs studied so far, discuss ways of their prediction, mechanical properties. In contrast to clas- sical multielement/multiphase alloys, only single-phase multielement alloys (solid solutions) represent the basic concept underlying HEAs as mixing-entropy stabilized homogenous materials. The literature overview is com- plemented by own studies demonstrating that the alloys CrFeCoNi, CrFeCoNiAl 0.3 and PdFeCoNi homogenized at 1300 and 1100 ° C, respectively, for 1 week are not single- phase HEAs, but a coherent mixture of two solid solutions.

/pdf/single-phase-high-entropy-alloys-an-overview-2v82mzb3c8.pdf

Single-phase high-entropy alloys - an overview

High-entropy alloys exhibit exceptional mechanical properties at cryogenic temperatures, due to the activation of twinning in addition to dislocation slip. The coexistence of multiple deformation pathways raises an important question regarding how individual deformation mechanisms compete or synergize during plastic deformation. Using in situ neutron diffraction, we demonstrate the interaction of a rich variety of deformation mechanisms in high-entropy alloys at 15 K, which began with dislocation slip, followed by stacking faults and twinning, before transitioning to inhomogeneous deformation by serrations. Quantitative analysis showed that the cooperation of these different deformation mechanisms led to extreme work hardening. The low stacking fault energy plus the stable face-centered cubic structure at ultralow temperatures, enabled by the high-entropy alloying, played a pivotal role bridging dislocation slip and serration. Insights from the in situ experiments point to the role of entropy in the design of structural materials with superior properties.

/pdf/cooperative-deformation-in-high-entropy-alloys-at-ultralow-ovzwzipxxh.pdf

Cooperative deformation in high-entropy alloys at ultralow temperatures

I N a review paper of this nature it is impossible to cover adequately all aspects of such a large subject as the mechanical properties of materials at low temperatures, and any choice of topics must inevitably leave some areas completely uncovered and others barely indicated. The selection of topics has been made on personal preference but it is hoped that this paper will convey some idea of the present position in the major branches of this subject.

D.A. Wigley

Papers

Mechanical Properties of Materials at Low Temperatures