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.
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.
Zhiming Li, Alfred Ludwig, Alan Savan, Hauke Springer, and Dierk Raabe, "Combinatorial metallurgical synthesis and processing of high-entropy alloys," Journal of Materials Research 33 (19), 3156-3169 (2018).
Zhiming Li, Cemal Cem Tasan, Konda Gokuldoss Pradeep, and Dierk Raabe, "A TRIP-assisted dual-phase high-entropy alloy: Grain size and phase fraction effects on deformation behavior," Acta Materialia 131, 323-335 (2017).
Zhiming Li and Dierk Raabe, "Strong and Ductile Non-equiatomic High-Entropy Alloys: Design, Processing, Microstructure, and Mechanical Properties," JOM-Journal of the Minerals Metals & Materials Society 69 (11), 2099-2106 (2017).