Details

Autor(en) / Beteiligte

• Yao, J.Y.
• Taylor, J.A.

Titel

Characterisation of intermetallic particles formed during solution treatment of an Al–7Si–0.4Mg–0.12Fe alloy

Ist Teil von

• Journal of alloys and compounds, 2012-04, Vol.519, p.60-66

Ort / Verlag

Kidlington: Elsevier B.V

Erscheinungsjahr

2012

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• ► It is concluded in this work that the fine needle-like particles formed during the solution treatment of the 356 type alloy are indeed β phase plates similar to those frequently observed in as-cast aluminium alloys but of much finer sizes, most likely formed by precipitation in the vicinity of the dissolving π phase particles. ► The crystal structure of the needle-like particles, as examined by selected area electron diffraction, can be essentially indexed as either the A-Centred Monoclinic lattice [18] or the Orthorhombic lattice [25]. ► The particles appear to co-exist in two distinct forms: single crystal particles and composite micro-constituent particles. When Fe-containing Al–7Si–xMg alloys are solution-treated, usually as the initial stage of a T6 heat treatment, some of the π-Al9Mg3FeSi5 phase present in the as-cast alloy transforms into fine needle-like intermetallic particles (as seen on a polished surface). These precipitated needles, speculated to be β-Al5FeSi phase, have not been definitively characterised to date. In this work, electron microscopy characterisation by various techniques was conducted to assess the nature (i.e. the composition, morphology and crystallography) of these particles to verify or otherwise the validity of the above hypothesis. It is found that the particles are indeed β phase platelets, of the same Al5FeSi or Al4.5FeSi stoichiometry as particles formed during solidification. Close observation of their crystallographic structure suggests fine-scale internal complexities in some of the particles.