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Time-Dependent Rheological Properties of Semi-Solid Metal Alloys

  • Semi-solid metal alloys, as used in thixoforming, have a special microstructure of globular grains suspended in a liquid metal matrix. The complex rheological properties are strongly influenced by the local solid fraction, particle shape, particle size and state of agglomeration. There is a high demand for models and software tools allowing the simulation of semi-solid casting processes. The material under investigation is a tin-lead alloy (Sn-15%Pb) which exhibits a similar microstructure to aluminium alloys. The experiments were performed with a concentric cylinder rheometer of the Searle type. Initially, the liquid alloy is cooled down to the semi-solid range under constant shearing and then kept under isothermal conditions for further experimentation. Based on the experimental data, a single-phase model has been derived where the semi-solid alloy is regarded as a homogeneous material with thixotropic properties and the microstructure is characterised by a structural parameter. The model consists of two parts: the equation of state, including a finite yield stress, and a rate equation for the structural parameter. The model equations are employed in numerical software and used for the simulation of characteristic filling cases and the comparison with the conventional filling.

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Author:Michael Modigell, Johannes Koke
Title (English):Time-Dependent Rheological Properties of Semi-Solid Metal Alloys
Parent Title (English):Mechanics of Time-Dependent Materials
Document Type:Article
Year of Completion:1999
electronic ID:Zur Anzeige in scinos
Release Date:2020/01/06
Tag:modelling; semi-solid materials; simulation; suspensions; thixoforming; thixotropy
First Page:15
Last Page:30
Faculties:Fakultät MKT / Institut für Duale Studiengänge
DDC classes:600 Technik, Medizin, angewandte Wissenschaften / 620 Ingenieurwissenschaften und Maschinenbau
Review Status:Veröffentlichte Fassung/Verlagsversion