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Solidification and Microstructure Characteristics of the AlMg9 alloy

Recently, foundry Al-Mg alloys play an important role in overall foundry industry of light metals due to their high strength and ability of precipitation hardening for higher magnesium contents. Influence of the cooling rate on the solidification and microstructure development of AlMg9 alloy have been investigated in this paper. Cooling has been performed by the established rates of 0, 17 ; 3 ; 7, 55, and 150 K/s. Significant temperatures of phase changes have been accompanied and identified through simultaneous and simple thermal analysis, as well as through the numerical modeling by ThermoCalc which enabled working out of corresponding physical models. Microstructure characteristics analysis has been performed on the optical, as well as on the scanning electron microscope (SEM) which has resulted in visual recognition of individual phases on their morphology basis. Chemical composition determination of each phase was carried out by the energy dispersive specter (EDS) by which the identification of Alx(MnFe)ySiz, Mg2Si and Al8Mg5 phases were performed. Phase analysis, surface area, elongation and number of grains per surface area (NA) of the corresponding microstructure were established related to the cooling rates.

Al-Mg alloy; cooling rate; thermal analysis; microstructure; grain size

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