Complex Systems Seminar: Ming-Wei Liu: "Mean-Field Theory of Slip Avalanches in High-Entropy Alloys"

Slip avalanches in plastically deformed crystals exhibit collective dynamics governed by stick-slip motion and long-range interactions. Mean-field theory provides a powerful framework for predicting universal scaling laws and critical exponents. In this talk, I will apply it to analyze serration statistics of the Portevin–Le Chatelier (PLC) effect in high-entropy alloys (HEAs). A mean-field model incorporating dynamic weakening and healing captures the strong solute–dislocation interactions characteristic of HEAs. Weakening induces system-spanning runaway events with distinct scaling laws for avalanche size, duration, and peak velocity compared to smaller slip events. By analyzing avalanche statistics of serration data from high-temperature tensile tests of refractory HEAs, we distinguish between slow avalanches, which exhibit scale-invariant temporal profiles, and fast runaways with a characteristic Gaussian peak, reflecting rapid nucleation. A timescale analysis further reveals a non-equilibrium phase diagram linking temperature and strain rate to solute–dislocation interactions

Ming-Wei Liu, PhD Candidate, UIUC

Host: Istvan Kovacs

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