Light Metals 2012 pp 431-434 | Cite as
The Influence of Solution Treatment on the High-Temperature Strength of Al-Si Foundry Alloys with Ni
Abstract
Al-Si-Ni alloys can be considered as a coarse two-phase system where a hardening effect is caused by load transfer to an interconnected rigid network of eutectic Si and aluminides. In the course of a solution treatment the contiguity of the eutectic phase is reduced, which leads to a decrease of strength. However, solution treatment is necessary to obtain a high supersaturation of elements in the Al-solid solution, which contribute to high-temperature strength due to precipitation hardening. Despite Ostwald ripening, the distribution of secondary precipitates is still dense enough to act as dislocation obstacles, as was confirmed by TEM-analysis. This work discusses the influence of heat treatments on the elevated-temperature strength of Al-Si foundry alloys with Ni and analyzes the active strengthening mechanisms. In order to investigate the effect of a solution treatment on the high-temperature strength of Ni-containing Al-Si foundry alloys, the tensile properties of various eutectic alloys were determined at 250°C after long-time exposure to test temperature.
Keywords
Al-Si foundry alloy Solution treatment High-temperature strength Hardening effect NickelPreview
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