Papers by Author: A.J. Morton

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Authors: Ian J. Polmear, G. Pons, H. Octor, C. Sanchez, A.J. Morton, Wendy Borbidge, S. Rogers
Authors: Yu Man Zhu, A.J. Morton, Jian Feng Nie
Abstract: The structure of intermetallic phases and planar defects in the as-cast and the solutiontreated microstructures of a Mg-8Y-2Zn-0.6Zr (wt%) alloy are characterized using transmission electron microscopy. The alloy was produced by permanent mould casting and solution treated at 500 °C. It is found that the intermetallic particles in the as-cast microstructure have a monoclinic structure. An appreciable amount of intermetallic particles is still retained along grain boundaries after solution treatments for up to 60 hrs. However, the structure of the retained intermetallic particles changes gradually from monoclinic to hexagonal during the solution treatments. Some planar defects are also detected in the as-cast and the solution-treated (1 hr) microstructures. These defects have characteristic features of stacking faults.
Authors: Roger N. Lumley, Ian J. Polmear, A.J. Morton
Authors: Roger N. Lumley, Ian J. Polmear, A.J. Morton
Authors: Roger N. Lumley, A.J. Morton, Ian J. Polmear
Authors: B. Décamps, Jean-Michel Pénisson, M. Condat, L. Guétaz, A.J. Morton
Authors: A.J. Morton
Authors: Roger N. Lumley, J. Buha, Ian J. Polmear, A.J. Morton, A. Crosky
Abstract: This paper reviews some of the practical outcomes of exploiting secondary precipitation during the heat treatment of aluminium alloys and discusses current understanding of this phenomenon. Recent studies have utilised the techniques of positron annihilation spectroscopy (PAS), 3D atom probe (3DAP) as well as the more traditional transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) to investigate early precipitation events that occur during secondary ageing at low temperatures (~20-65°C). This work has confirmed that clustering and GP zone formation can modify the nature and distribution of precipitates that form when ageing is subsequently resumed at more elevated temperatures. Prospects for achieving further improvements in heat treatment schedules and alloy compositions to take greater advantage of secondary precipitation are also considered.
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