Rheocasting von Aluminium-Silizium-Legierungen: der RheoMetal Prozess im Fokus

Translated title of the contribution: Rheocasting of Aluminum-Silicon Alloys: focus on the RheoMetal Process

Teo Stoisser

Research output: ThesisMaster's Thesis

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Abstract

The RheoMetalTM process utilises the stirring of an Enthalpy Exchange Material (EEM) to produce a semi-solid melt. The absence of complex temperature regulation renders it a reproducible and promising rheocasting process for industrial applications. This master’s thesis aims to determine the differing behaviours of the alloys AlSi7MnMg, AlSi4MnMg, and 6082 under identical process conditions. Furthermore, the investigation of the EEM focuses on its path travelled and its solidification pattern within the casting part, employing the tracer element tantalum. To treat the proposed research questions the following steps have been implemented: Fundamental research on the solidification behaviour of the alloys was conducted by using the Thermo-Calc software. For the EEM tracing, tantalum containing EEMs were cast in a sand mould. After the casting, analyses were performed using differential scanning calorimetry (DSC), light microscopy combined with Weck-etching, and scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX). Utilizing the RheoMetalTM process, a fully formed casting part was produced from each alloy. Microstructural analysis of the AlSi7MnMg and AlSi4MnMg alloys revealed a clear formation of the α-Aluminium particles. The heating curves of the differential scanning calorimetry between the rheocasting and pre-material samples showed no significant difference. Determination of the solid fraction, facilitated by Weck etching, yielded a solid fraction of 18.69 ± 4.59 % for the AlSi7MnMg-Rheo sample. One possible explanation for this value is provided by the challenges in computer-aided analysis due to uneven etching and the cooling point within the casting mould. The same issue impeded an evaluation of the AlSi4MnMg-Rheo and 6082-Rheo samples. The tantalum contained within the EEM could not be detected in the casting part via scanning electron microscopy.
Translated title of the contributionRheocasting of Aluminum-Silicon Alloys: focus on the RheoMetal Process
Original languageGerman
QualificationDipl.-Ing.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Pammer, Maria, Co-Supervisor (internal)
  • Hofer-Hauser, Peter, Supervisor (internal)
Award date20 Dec 2024
DOIs
Publication statusPublished - 2024

Bibliographical note

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Keywords

  • RheoMetal
  • rheocasting
  • semi-solid
  • aluminium silicon alloys
  • slurry
  • EEM
  • Enthalpy Exchange Material

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