Morphological features of structures obtained by two-stage crystallization of Al – 7.5 wt. % Si alloy
DOI: https://doi.org/10.15407/foundry-metallurgy-2024.040
А. G. Borisov,
V. I. Belik
Physico-Technological Institute of Metals and Alloys of the NAS of Ukraine, Kyiv
Morphological features of structures obtained by two-stage crystallization of Al – 7.5 wt. % Si alloy were studied. Alloy with composition Al - 7,5wt. % Si; 0,29 wt. %Mg; 0,12 wt. %Fe; 0,028 wt. % Mn; 0,005 wt. %Cu; 0,0015 wt. % Ti. was used. To control the formation of the structure of the initial alpha phase, thermal, temporal, and force effects on the melt in a thermostat were used. The formation of the structure of the final alpha phase was achieved using various thermal modes of solidification of the casting from a liquid metal suspension in a metal mold.
As a result of the experiments, almost the entire spectrum of morphologies characteristic of semi-solid rheocasting processes of A356 was obtained.
The possibility of controlling the structure of pseudocomposites for A356 alloy by combining the morphologies of the initial and final α-phases has been experimentally demonstrated. The formation of such pseudocomposites is also fundamentally possible for other alloys, which are characterized by the formation of both dendritic and rosette mophologies, for example, alloys based on Al, Cu, Fe, Co, Ni.
Application of various methods of melt treatment at the first stage of crystallization makes it possible to obtain three different types of morphology of the initial alpha phase - dendritic, rosette and globular.
Keywords: Al-based alloys, melt treatment, crystallization, microstructure