High-Entropy Alloys

High-Entropy Alloys

The goal of our group is to develop novel high-entropy alloys (HEAs) with exceptional mechanical, physical and chemical properties based on the understanding of their structure-properties relations. This is being achieved by using the advanced experimental techniques and the state-of-the-art theoretical methods.

Figure 1: Strength-ductility profiles of various classes of metallic materials including our recently developed HEAs.

Conventional alloy design over the past centuries has been constrained by the concept of one or two prevalent base elements. As a breakthrough of this restriction, the concept of HEAs opens a new realm of numerous opportunities for investigations in the huge unexplored compositional space of multi-component alloys.

As a typical example shown in Figure 1, while conventional alloys use strengthening mechanisms such as grain boundaries, dual-phase structure, dislocation interactions, precipitates and solid solution (e.g. steels, Ti-alloys, Al-alloys), our recently developed novel interstitial TWIP-TRIP-HEAs concept combines all available strengthening effects, namely, interstitial and substitutional solid solution, TWIP, TRIP, multiple phases, precipitates, dislocations, stacking faults and grain boundaries. This leads to the exceptional strength-ductility combination of the novel HEAs, exceeding that of most metallic materials.

Our research group (High-Entropy Alloys) conducts the state-of-the-art research work employing novel experimental-theoretical methodologies (e.g., EBSD, ECCI, FIB-APT, TEM, Calphad and DFT; Figure 2) in the following specific aspects:

  • Excellent strength-ductility combination of transitional metal HEAs;
  • Resistances to hydrogen-embrittlement and corrosion of HEAs
  • Light-weight high-strength HEAs
  • High-temperature refractory high-strength HEAs
  • Multifunction of HEAs
  • Defects, segregations and thermodynamics in HEAs
  • In-situ observation of deformations in HEAs under electron microscopes

These aspects are strongly interconnected and facilitate an extensive collaboration network with national and international experts.

Figure 2: Representative microstructural information obtained from an interstitial TWIP-TRIP-HEA sample by combining multiple advanced characterization techniques. ECCI: Electron channeling contrast imaging; EBSD: Electron backscatter diffraction; TEM: Transmission electron microscopy; APT: Atom probe tomography; TWIP: Twinning-induced plasticity; TRIP: Transformation-induced plasticity.

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