Atomic scale understanding of the TRIP-assisted dual-phase high-entropy alloys
In this project, we aim to achieve an atomic scale understanding about the structure and phase transformation process in the dual-phase high-entropy alloys (HEAs) with transformation induced plasticity (TRIP) effect. Aberration-corrected scanning transmission electron microscopy (TEM) techniques are being applied to obtain the related information at atomic resolution.
The displacive phase transformation from face-centered cubic (FCC) γ phase to hexagonal close-packed (HCP) ε martensite and the reverse transformation (ε→γ) play a key role in enhancing the mechanical properties of FCC alloys, especially for the recently developed TRIP-assisted dual-phase HEAs. These phase transformations strongly depend on the stacking fault energy, instant temperature and stress condition during mechanical loading.
Within the statistical limits of TEM and energy dispersive spectroscopy (EDS), no indication for solute segregation and precipitation were found at interface between FCC γ and HCP ɛ phase in the dual-phase HEA. In the deformed samples, a mixed sub-structure consisting of γ nano-lamellas and twins was observed in HCP ɛ block. We also investigated the local displacive phase transformation at annealing twin boundaries in the dual-phase HEA. A systematic study is being carried out to understand the atomic structure of such annealing twin boundaries and the corresponding effect on phase transformation process.
International researcher team presents a novel microstructure design strategy for lean medium-manganese steels with optimized properties in the journal Science
The main aspect of this project is to understand how hydrogen interacts with dislocations/ stacking faults at the stress concentrated crack tip. A three-point bending test has been employed for this work.
Understanding the deformation mechanisms observed in high performance materials, such as superalloys, allows us to design strategies for the development of materials exhibiting enhanced performance. In this project, we focus on the combination of structural information gained from electron microscopy and compositional measurements from atom probe…