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Philippe Marcus opened a general discussion of the paper by Roger Newman: Should the passive lm not be signicantly involved in pit initiation (as you suggest), how would you explain that the time to initiation is very much dependent on the nature of the passive lm?Roger Newman responded: I never said that the passive lm is not involved in pit initiation. I understand (of course) that longer passivation gives a longer induction time for pitting. What I say is that the effects of parameters like alloy composition, environment composition, potential, and temperature, are not easily accommodated (at least not predictively) within a passive lm breakdown model, but fall out naturally from a modied Galvele type of model that uses pitting potential data (or, if one has the time, lower extremes of pitting potential distributions). Now I don't know whether or not the nest details of lm breakdown, detectable at the pA level or lower in electrochemical experiments (not nA to mA -those are already pits), and/or on very pure, at alloy surfaces, follow the same rules that we nd using pitting potentials on industrial or semi-industrial alloys. Those measurements have not been done. Actually I don't think stainless steel is necessarily the best model system for such studies. Under certain conditions, as shown by Bardwell many years ago, iron shows blizzards of pits that are clearly not impurity-particle-related; probably aluminum too. In stainless steel we really don't know whether pit initiation ever occurs without a microcrevice and/or an impurity particle.From the viewpoint of practical utility, the Galvele type of approach clearly has the advantage. The Critical Pitting Temperature (CPT) is a propagation-related transition below which metastable pits never become stable at any potential. My group has published extensively on that. One can make a foolproof, if expensive, † Electronic supplementary information (ESI) available: SVET scans movie. See

The properties of the interfacial transition zone (ITZ) of steel fiber and the bulk matrix were quantified using the backscattered electron imaging analysis (BSE-IA) and the scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), and their relationship with the mechanical properties of steel fiber-reinforced mortars was studied. The water and binder ratio (w/b) of mortar, the amount of silica fume and steel fiber were varied. From the quantitative analysis, a higher build-up of calcium hydroxide was found from the steel fiber's interface up to 2 or 4 lm distance away and its buildup was reduced with the 10% cement replacement by silica fume. Porosity in the ITZ and bulk matrix decreased the fracture energy, compressive energy and debonding load of steel fiber-reinforced mortar. However, its effect became marginal if a substantial amount of C-S-H or steel fibers appeared in the ITZ and bulk matrix, which increased the studied mechanical properties.

ABSTRACT:The mechanical behavior of semicrystalline Nylon 11 was studied at strain rates between 10 Ϫ3 and 8800 s Ϫ1. X-ray diffraction and DSC were employed to examine the crystal structure and the crystallinity content. The as-received material comprised a mixed structure of a predominately triclinic (␣) form. DSC revealed that the material gave rise to two melting peaks. The compressive flow stress of Nylon 11 experienced a large increase at 1200 s Ϫ1 and decreased at higher strain rates. The maximum level of the flow stress corresponded with a higher level of crystallinity and a structure mainly of a pseudohexagonal form. The subsequent drop in stress at higher rates was associated with a decrease in the crystallinity content and a mixed crystal structure, different from that observed in the as-received material. After compression, the low melting peak disappeared and the material melted over an increased temperature range.

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