Refinement of the Magnesium–Aluminium Alloy Microstructure with Zirconium

Autor: Cezary Rapiejko, Dominik Mikusek, Bartłomiej Januszewicz, Krzysztof J. Kubiak, Tadeusz Pacyniak
Jazyk: angličtina
Rok vydání: 2022
Předmět:
Zdroj: Materials, Vol 15, Iss 24, p 8982 (2022)
Druh dokumentu: article
ISSN: 1996-1944
DOI: 10.3390/ma15248982
Popis: The magnesium–aluminium alloy AZ91 was inoculated with zirconium to refine the microstructure. Six different concentrations of zirconium content were tested, ranging from 0.1 to 0.6 wt %, and compared to the baseline AZ91 alloy without modification. Melted metal was poured into a preheated ceramic mould and the temperature was measured and recorded during the solidification. The derivative and thermal analysis (DTA) was performed to compare the crystallisation dynamics. Formed microstructure was analysed using an optical microscope, scanning electron microscopy (SEM-EDX) and energy dispersive X-ray spectrometry (XRD). The chemical composition was measured using an arc spectrometer. The time of solidification was shortened for the samples with a concentration of zirconium 0.3 wt % and the microstructure was refined. The level of grain refinement remained below 10% and the grain shape was changed to more spherical shapes. Both the primary magnesium and eutectic phases were modified. However, at a low concentration of zirconium (0.1 and 0.2 wt %), the primary grain size was increased. Therefore, the optimal zirconium concentration was 0.3 wt %. Larger concentrations (0.4 to 0.6 wt %) did not provide any additional benefit. Theoretical analysis showed that some Al3Zr intermetallic phases can form, which was confirmed on the derivate curve of the thermal analysis, and SEM-EDS and XRD analyses.
Databáze: Directory of Open Access Journals
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