OBRABOTKAMETALLOV Vol. 27 No. 1 2025 168 MATERIAL SCIENCE Fabrication and characterization of Al-7Si alloy matrix nanocomposite by stir casting technique using multi-wall thickness steel mold Khaled Abdelaziz 1, 2, a, Dalia Saber 1, 3, b, * 1 Materials Engineering Department, Faculty of Engineering, Zagazig University, Zagazig, 44519, Egypt 2 Mechanical Engineering Department, College of Engineering, Taif University, PO Box 11099, Taif, 21944, Saudi Arabia 3 Industrial Engineering Program, Mechanical Engineering Department, College of Engineering, Taif University, PO Box 11099, Taif, 21944, Saudi Arabia a https://orcid.org/0000-0001-9139-548X, kalidelaziz@gmail.com; b https://orcid.org/0000-0002-7349-1723, daliasaber13@yahoo.com Obrabotka metallov - Metal Working and Material Science Journal homepage: http://journals.nstu.ru/obrabotka_metallov Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science. 2025 vol. 27 no. 1 pp. 155–171 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2025-27.1-155-171 ART I CLE I NFO Article history: Received: 26 October 2024 Revised: 15 November 2024 Accepted: 28 December 2024 Available online: 15 March 2025 Keywords: Metal matrix composites (MMCs) Mold wall thickness TiO2 nanoparticles Mechanical properties ABSTRACT Introduction. The Al-7Si is considered one of the key aluminum alloys due to its favorable combinations of casting and mechanical properties. Metal matrix composites (MMCs) reinforced with ceramic particles are widely used in high-tech industries such as military, automotive, aerospace, and electrical engineering. The purposes of this study are threefold: (1) to investigate the feasibility of producing composite materials based on the Al-7Si alloy reinforced with varying amounts of TiO2 nanoparticles using a stir casting technique; (2) to investigate the eff ect of mold wall thickness on the microstructure and mechanical properties of the Al-7Si alloy during solidifi cation; and (3) to analyze the infl uence of the reinforcing component content on the mechanical properties and wear resistance of the resulting composite materials. Methodology. Metal matrix composite materials based on the Al-7Si alloy, containing 0, 2, 4, and 6 wt. % TiO2 nanoparticles, were fabricated using a stir casting technique. Cylindrical specimens with a diameter of 15 mm and a length of 18 mm were prepared for metallographic and mechanical testing. Results and discussion. It is found that the solidifi cation rate increases with increasing mold wall thickness. This leads to an increase in the cooling rate and, consequently, to the formation of a fi ner-grained structure. The microstructure of the casting demonstrates a change in grain size from fi ne to coarse when transitioning from the outer surface (adjacent to the inner mold wall) to the inner part of the casting. As a result, the microhardness near the inner mold wall is higher. Density measurements indicate that composites with a higher amount of reinforcing particles exhibit greater porosity. Furthermore, the results of hardness and wear tests reveal that an increase in the TiO2 particle content leads to increased hardness and a signifi cant reduction in the wear rate of the composite materials. For citation: Abdelaziz K., Saber D. Fabrication and characterization of Al-7Si alloy matrix nanocomposite by stir casting technique using multi-wall thickness steel mold. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science, 2025, vol. 27, no. 1, pp. 155–171. DOI: 10.17212/1994-6309-2025-27.1-155-171. (In Russian). ______ * Corresponding author Saber Dalia, D.Sc. (Engineering), Professor Materials Engineering Department, Faculty of Engineering, Zagazig University, 44519, Zagazig, Egypt Tel.: 0096645355163, e-mail: daliasaber13@yahoo.com References 1. Liu J., Chen X., Wang W., Zhao Y., He N. Eff ect of TiB2 nanoparticle content on the microstructure and mechanical properties of TiB2/Mg-4Al-1.5Si composites. Materials, 2023, vol. 16, p. 2852. DOI: 10.3390/ ma16072852. 2. Nassar A.E., Nassar E.E. Properties of aluminum matrix nano composites prepared by powder metallurgy processing. Journal of King Saud University – Engineering Sciences, 2017, vol. 29 (3), pp. 295–299. DOI: 10.1016/j. jksues.2015.11.001. 3. Tahamtan S., Halvaee A., Emamy M., Zabihi M.S. Fabrication of Al/A206–Al2O3 nano/micro composite by combining ball milling and stir casting technology. Materials and Design, 2013, vol. 49, pp. 347–359.
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