Research Projects - Alloy development / High entropy alloys

In conventional metallic materials, the increase of strength by dislocation hardening generally sacrifices ductility. In recent years, a novel alloy design concept has drawn great attention, where multi-principal elements are mixed at equimolar or near equimolar concentrations to form highly concentrated solid solutions, termed high-entropy alloys (HEAs). To promote the wide use of HEAs as structural materials, it is highly desirable to improve the strength of HEAs while maintaining good ductility. In this project, we demonstrate an approach to improve the strength and ductility simultaneously by tuning the stacking fault energy and deformation mechanism in single-phase face-center cubic (FCC) high-entropy alloys (HEA) as shown in Fig. 1. more

One of the still mysterious effects in high entropy alloys (HEAs) is how atoms in highly supersaturated solid solutions locally arrange in the given crystal lattice. Recent investigations indicate that chemical short range order (SRO) and local compositional fluctuations are characteristic for HEAs, which can significantly affect the mechanical properties. In this project, the characteristics of short range order and local compositional fluctuations in refractory high entropy alloys are revealed at atomic resolution and are correlated to micro- and macroscopic mechanical properties. more

Conventional alloy development methodologies which specify a single base element and several alloying elements have been unable to introduce new alloys at an acceptable rate for the increasingly specialised application requirements of modern technologies. An alternative alloy development strategy searches the previously unexplored central regions of multi-component phase space for alloys whose properties can be tuned with a greater degree of control than previously achievable. The targeted exploration of composition spaces containing five or more elements presents a significant challenge due to the vast number of possible alloy combinations. Novel approaches are required to efficiently map the boundaries of unique phase and morphology formation domains over large regions of multi-principle-element composition space. more

To make electricity production more sustainable requires the development of novel high-temperature-stable materials capable of operating in harsh environments and not requiring large amounts of expensive and rare elements.  Conventional alloy development methodologies which specify one or two base elements and several alloying additions have been unable to introduce new alloys with the required combination of properties for these high temperature applications.  An alternative alloy development strategy searches the relatively unexplored central regions of multicomponent phase space for multi-principle-element alloys which can be optimised with a greater degree of control than possible using conventional alloying techniques. more