Norwegian-Japanese Al-Mg-Si Alloy Precipitation Project

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The project is built over two PhD programs; (I) 'Trace elements during recycling of 6xxx alloys and their effect on precipitation' and (II) 'Vacancies in aluminium alloys in a context of trace elements and recycling' where one student will be Japanese and the other will stay in Japan up to one year. The program applies for 3 months exchange of guest researchers between NTNU and Toyama Univ. The overall consortium consists of 5 partners; NTNU, SINTEF, Hydro, Toyama University and Tokyo Institute of Technol ogy. In addition, Japanese Aluminium industry supports the project, as shown by support letters. PhD project (I) sets out to characterise effects that trace elements (TE) in 6xxx series Al alloys have on nucleation and precipitation. Effects on nucleatio n could be good or bad depending on amount, type or combination of TE. Possible effects on precipitates are; modifcation of atomic structure, change in relative fractions of precipitate, sizes or quantities, or formation of new types. A variety of advance d TEM methods needs to be used (e.g. high resolution TEM, nanobeam diffraction) to quantify precipitates, and simulation/calculation tools (such as MSLS) are available to investigate structure. Quantum mechanical methods are likely to be used concerning s tability calculations and verify the MSLS refined structures. Experiments on a dedicated high angle annular dark field scanning TEM (HAADF-STEM) instrument are suggested. PhD project (II) will also need to employ some of the methods above. However, a mai n aim with this project is building competence concerning (investigation of) vacancies and their relation with TE. To find adequate equipment is therefore essential. Positron Annihilation Spectroscopy (PAS) is a relatively recent tool used to study aspect s of vacancies, and will be of special focus. An important task of PhD II is to establish cooperation with a PAS lab, perform suitable experiments and build up competence concerning this technique.