This work tackles the methodological challenge of rationalizing symmetric-cell cycling data from a materials-science perspective, through experiment replication, mathematical modelling, and tomographic imaging. Specifically, we address Zn electrode cycling in alkaline electrolyte with and without adding tetrabutylammonium bromide (TBAB). This additive is known from literature, but its practical impact is jeopardized by lack of in-depth understanding of its behaviour. Electrochemical testing was carried out at practically relevant current densities and the effect of variations of operating conditions was taken into account. The physical chemistry underlying cell potential profiles, has been modelled mathematically, accounting for: electrokinetics, mass-transport, electrode shape change and passivation. In particular, we disclosed an unexpected joint effect of TBAB and current density on passivation time: tomography allowed to rationalise this behaviour in terms of precipitate morphology.

Metallurgical optimization of engineering alloys is traditionally addressed to improve the overall performance from a mechanical point of view. Grain size is one of the most influential and critical parameters to be controlled in nickel alloys, especially in the high-temperature shaping process and final solution treatment, since it can irremediably damage the alloy performance. For this reason, grain coarsening of alloy 625 was investigated in the temperature interval from 980 to 1150 °C ranging from 0.5 to 6 h. The grain-coarsening data were fitted via regression analysis as a function of time and temperature to develop a predictive model. Grain boundary strengthening was studied by hardness and tensile tests, and the relationships between the grain size and the mechanical properties were finally determined by regression analysis. Such equations were included in a thermo-metallurgical model able to predict the mechanical properties after annealing treatment. This predictive model was validated on a forged tube subjected to solution annealing at 1150 °C for 90 min. Then, it was finally used to compare different microstructural conditions in terms of the alloy impact on the environment.

An original simplified finite element model is proposed to simulate the effects of non-penetrating ballistic impacts causing the so-called bullet splash phenomenon (complete bullet fragmentation), while no fragmentation is caused to the target. The model is based on the Arbitrary Lagrangian Eulerian formulation (ALE) and it simulates the impact as a fluid-structure interaction. The bullet splash phenomenon has been tested by experimental analyses of AISI 304L plates impacted by 9x21 FMJ (full metal jacket) bullets. The model has been developed with the aim of creating a simplified approach to be used in the industry and forensic sciences to simulate the non-penetrating interaction of soft impactors with hard targets. Comparisons between evidence and simulation results lead to the conclusion that the proposed approach can be used in a conservative way to estimate both local and global effects of bullet-splash phenomena.

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Summary Failure analysis normally requires many forms of investigation, but visual examination is the most used amongst all possible techniques. However, as the legal climate for fire investigation is becoming more rigorous, fire researchers need to work differently. In other words, to be technically defensible, expert testimony must be built on scientific data. To this aim, in‐depth microstructural analyses of materials are particularly suitable to define the fire scene. This paper discusses some of the basic metallurgical theories used in failure analysis of copper, steel and aluminium alloy components involved in fire situations. Some components that can be easily found in fire and arson scene were submitted to simulated fire for indicated time and temperature. The collected samples were than examined by optical microscopy, scanning electron microscopy and energy‐dispersive spectroscopy. Oxidation, recrystallization, second‐phase precipitation and melting were some of the features observed on samples that can be strictly related to the thermal effect of fire. On the basis of these metallurgical results and starting from the evidence that different exposure temperatures can induce different metallurgical modifications, it is possible to define the temperature range experienced by various components, thus suggesting the fire dynamic during the incident. Copyright © 2014 John Wiley & Sons, Ltd.