Surrogate model-based assessment of particle damage behaviour of AlZnMg alloy

Recent research has found some intermetallic compound particles with even stronger hydrogen trapping capacity (e.g., Al₇Cu₂Fe) than the age-hardening precipitates that are reported to be the origin of hydrogen embrittlement in aluminium. Such intermetallic compound particles can reduce hydrogen concentration at the interface between the precipitates and aluminium by absorbing hydrogen in their interiors, thus preventing the hydrogen embrittlement of aluminium. However, this cannot be achieved if the particles, which have absorbed large amounts of hydrogen, are damaged due to hydrogen embrittlement. In this study, the hydrogen embrittlement of aluminium was observed in situ by X-ray CT, and the damage behaviour was analysed of all the particles that were located in the gauge section of a single tensile specimen. After exhaustive quantification of the size, shape, and spatial distribution of the particles, coarsening processes identified highly correlated design variables. Subsequently, particle damage behaviour was analysed utilizing a surrogate model using a support vector machine. The damage to Al₇Cu₂Fe particles could be described only by design variables representing size and shape, while those representing spatial distribution were removed through the coarsening processes. No change was observed in the damage behaviour of Al₇Cu₂Fe particles with increasing hydrogen concentrations, and it was concluded that the dispersion of Al₇Cu₂Fe particles is effective in preventing hydrogen embrittlement of aluminium. The contribution of damaged particles to the formation of fracture surfaces and the damage behaviour of Mg₂Si particles, where damage is accelerated by hydrogen, were also analysed.