Dynamic precipitation of Al–Zn alloy during rolling and accumulative roll bonding

In this study, cold rolling was performed on a binary Al–20 wt%Zn alloy and dynamic precipitation identified for the first time in Al alloys under cold rolling. Zn clusters formed after application of 0.6 strain, and the Zn phase precipitated upon further increasing strain. Both grain refinement and rolling-induced defects are considered to promote Zn precipitation. The hardness of Al–Zn alloy initially increased with strain up to a strain of 2.9 and then decreased with increasing rolling strain. Dynamic precipitation greatly affects the strengthening mechanism of the rolled Al–Zn alloy under various strains.     

Coexistence of adjacent vacancy-ordered and eutectic phases in Al–Cu–Ni alloys

ABSTRACT

Copper-mould-cast Al–Cu–Ni alloys show adjacent coexistence of in situ grown ordered and eutectic phases. A bimodal microstructure of α–Al and eutectic α-Al+θ-Al₂Cu phases with length-scale hierarchy evolves during solidification. Microstructural analysis through Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) shows the presence of Vacancy-ordered phases (VOPs) with different morphologies in two different compositions.     

A new orthorhombic approximant of the icosahedral Al–Cu–Fe quasicrystal

We report on the formation of a new crystalline approximant phase of the icosahedral (i-)Al–Cu–Fe quasicrystal. This phase is formed during sintering of Al-based composites reinforced with i-AlCuFeB quasicrystalline particles. The structure of this phase has been characterized by transmission electron microscopy (TEM) and high-resolution electron microscopy (HREM). TEM revealed that it is a B-centred orthorhombic phase with lattice parameters a = 1.166 nm, b = 1.195 nm and c = 3.44 nm. Its chemical composition, as determined by electron energy loss spectroscopy (EELS), is close to Al_76.9Cu_2.7Fe_20.4, with an average number of valence electrons per atom e/a of 1.92, similar to the value in all other approximants of the i-phase discovered thus far. Initial results on local atomic arrangements along one of its pseudo-5-fold axes are also presented.     

Phase-transformation-induced hardening in Zn–22Al alloys

A phase-transformation-induced hardening effect is reported in Zn–22Al (Al: 22?wt.%) alloys. The Zn–22Al specimens were held at 300?°C for 10?h and then quenched in water. A hardening effect took place in subsequent artificial aging at 100–200?°C, which was accompanied by a phase decomposition of a soft α ₂ phase and a grain coarsening. The phase-transformation-induced hardening affects the hardness more than the grain-coarsening-induced softening, which leads to the age-hardening phenomenon.     

Effects of Si addition on the microstructure evolution of Al–Cu–Mg alloys in the α + S + T phase field

The precipitation behaviour and age-hardening response of Al–1.5Cu–4.0Mg (wt.%) alloys microalloyed with Si have been investigated by means of hardness measurement, TEM and HRTEM. Compared to the ternary alloy, the quaternary alloys exhibit a higher hardness. It is found that the underaged microstructure in the Al–1.5Cu–4.0?Mg alloy contains some fine precipitates, which are identified as the T phase by FFT spectra. The peak-aged microstructures of the ternary alloy is dominated by the T phase, while the peak-aged microstructures of the Si-containing alloys are dominated by the S phase. The volume fraction of the S phase is found to increase as more Si is added.     

Cumulative integrated electromyographic activity of selected speech-related muscle groups of nonstutterers during massed oral readings

The electromyographic (EMG) integrated amplitude of masseter and laryngeal muscle groups were analyzed during five massed oral readings of 16 nonstuttering adult subjects. Reduction in dysfluencies were observed over the five trials as was a reduction in reading time across trials. Significant decreases in EMG activity across trials were found for the laryngeal, but not the masseter, EMG activity. This suggests that changes in vocal behavior thought to accompany adaptation are reflected in decreases in EMG activity of select speech-related muscle groups.     

High-temperature nanoindentation behavior of Al/SiC multilayers

Nanoscale Al/SiC composite laminates have unique properties, such as high strength, high toughness, and damage tolerance. In this article, the high-temperature nanoindentation response of Al/SiC nanolaminates is explored from room temperature up to 300°C. Selected nanoindentations were analyzed postmortem using focused ion beam and transmission electron microscopy to ascertain the microstructural changes and the deformation mechanisms operating at high temperature.     

Dying to live: mourning,melancholia and the adolescent process

The author reviews the main points in Freud's 1917 paper 'Mourning and Melancholia' and relates them to the process of both normal and troubled adolescent development. Using clinical examples she illustrates the ways in which the processes Freud describes in melancholia operate in some disturbed adolescents such that instead of mourning the lost objects of their childhood, they become stuck, remaining ambivalently attached to them and incorporating them into their final adult identity and sexual organization.

L'auteur passe en revue les points essentiels du texte de Freud « Deuil et mélancolie » (1917e [1915]) et les relie aux processus du développement, normal et pathologique, de l'adolescence. À l'aide d'exemples cliniques, il illustre la manière dont les processus décrits par Freud dans la mélancolie sont mis en ?uvre chez certains adolescents perturbés?:?au lieu de faire le deuil des objets perdus de leur enfance, ils restent bloqués dans l'ambivalence de leur attachement À ceux-ci et s'efforcent de les incorporer dans leur identité adulte et leur organisation sexuelle finale.

L'autrice passa in rassegna i punti principali dell'articolo del 1917 di Freud 'Lutto e melanconia' e li mette in relazione al processo dello sviluppo adolescenziale sia normale che disturbato. Utilizzando esempi clinici l'autrice illustra i modi in cui i processi che Freud descrive nella melanconia operano in alcuni adolescenti disturbati cosi' che invece del lutto per la perdita degli oggetti dell'infanzia, gli adolescenti rimangono incastrati e ambivalentemente attaccatti ad essi, incorporandoli nella loro identita' adulta finale e nell'organizzazione sessuale.

Die Autorin rezensiert die Hauptpunkte in Freud's Abhandlung ' Trauer und Melancholie' und bezieht sie auf den Prozess sowohl der normalen als auch der gestörten adoleszenten Entwicklung. Anhand von klinischen Beispielen illustriert sie die Art und Weise, in denen die Prozesse, die Freud in der Melancholie beschreibt, in einigen gestörten Jugendlichen operieren, so dass sie anstatt die verlorenen Objekte ihrer Kindheit zu betrauern, sie festgefahren sind und ambivalent an sie gebunden bleiben und sie letztlich in ihre Erwachsenenidentität und sexuelle Organisation inkorporieren.     

A Walk in the Invisible City

This essay discusses the performative interventions of the contemporary Belgian artist Francis Alÿs in Mexico City and how they create a critical focus on urban reality in the Latin American mega-cities, and outline ways of intervention and interaction in the modern disassociation of the city’s economical, social, and cultural levels, taking up the challenge to suggest their unity through imagination and art.     

Iron in solution with aluminum matrix after non-equilibrium processing: an atom probe tomography study

In this paper, we report on the influence of rapid solidification and severe plastic deformation on the solid solubility of Fe in Al. Atom probe tomography, for the first time, was performed on fine (3–4 μm diameter) and coarse (~100 μm) as-atomised Al-5 at.% Fe powder and cryomilled Al-5 at.% Fe powder. The atomised powders exhibited negligible Fe in solution with Al, whereas the cryomilled powder contained ~2 at.% Fe in solution. Moreover, our results suggest that severe plastic deformation is preferable to atomisation/rapid solidification for increasing the non-equilibrium solid solubility of Fe in Al.