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https://hku.zoom.us/j/91638414587?pwd=NHYQ3CEC6DCWU5zbpqvwXqvpt8eNU2.1

Meeting ID: 916 3841 4587

Password: 599331

Abstract:

In the deformation process of metals, dislocation slip is the main deformation mechanism. In some alloys, phase transformation-induced plasticity (TRIP) and twinning-induced plasticity (TWIP) occur due to the instability of the phases and the low stacking fault energies. In addition to these mechanisms, an uncommon deformation mode called kinking influences crystal plasticity. In the 1940s, a pioneering materials scientist Orowan observed this locally rotated but incompletely twin-symmetric deformation behavior during compression tests of single-crystal Zn and coined the term "kink". However, the mechanisms of kink formation and early-stage local lattice rotation remain unclear, and mechanistic modeling of these microscale torsional deformations is still under exploration. In this research, we reveal a new crystallographic relationship in deformation bands by subjecting CoCrNi medium-entropy alloy (MEA) single crystals to dynamic loading via a split-Hopkinson pressure bar (SHPB). Through crystallographic kinematic analysis and interrupted tests, we have completed the classification of several types of deformation bands and explore formation mechanisms of their kinking boundary. This work provides a new insight into the role of inhomogeneities in crystal plasticity, aiding the design of high-performance alloys and prediction of the plastic behavior of crystals.

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