Al-Si-Mg alloys containing 7% silicon are the most widely used aluminum foundry alloys owing to their good mechanical properties and excellent castability. Nevertheless, design engineers traditionally apply a design casting factor when designing cast components to ensure that proper strength will be obtained in spite of the recent emergence of techniques of control of the molten alloy quality on which depend, afterwards, the mechanical properties of the castings. / In this study, the feasibility of using electrical conductivity to non-destructively predict secondary dendrite arm spacing was investigated on both as-cast and heat treated alloys. In the as-cast condition, conductivity decreases linearly with increasing DAS from 30 $ mu$m, while, below 30 $ mu$m, conductivity readings are influenced by alloying elements retained in solid solution due to the fast solid state cooling rates. Conductivity changes with DAS are more important when the silicon morphology is finer i.e. the alloy modified. After heat treatment, the DAS-conductivity relationships become linear as a result of the homogenisation of the aluminum matrix, but the slopes of the lines are small and the accuracy of DAS determination does not extend below 15 $ mu$m. Conductivity is also greatly influenced by the degree of precipitation achieved during artificial aging so that the determination of DAS by conductivity measurement is best used after quenching (T4 condition).
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.60694 |
| Date | January 1992 |
| Creators | Charbonnier, A. (Alain) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Engineering (Department of Mining and Metallurgical Engineering.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001287715, proquestno: AAIMM74535, Theses scanned by UMI/ProQuest. |
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