Iranian Research Organization for Science and Technology Journal of Particle Science and Technology 2423-4087 9 2 2023 11 20 Fabrication method, microstructural characteristics, and hardness behavior of an interpenetrating phases hybrid aluminum/alumina-nanodiamond composite 63 71 1338 10.22104/jpst.2023.6538.1244 EN Hassan Zeinali Moghaddam Department of Materials Engineering, Faculty of Engineering, University of Sistan and Baluchestan, Zahedan, Iran Ghodratollah Roudini Department of Materials Engineering, Faculty of Engineering, University of Sistan and Baluchestan, Zahedan, Iran Hamed Khosravi Department of Materials Engineering, Faculty of Engineering, University of Sistan and Baluchestan, Zahedan, Iran 0000-0002-0217-8342 Journal Article 2023 10 17 In the present work, the addition effects of nanodiamond (ND) on the microstructure and hardness behavior of interpenetrating phases hybrid Al/Al₂O₃ metal matrix composites were investigated. The fabrication of the composites was done via a two-step process. In the first step, hybrid Al₂O₃-ND preforms were prepared, and then molten pure Al alloy was infiltrated into the preforms. The preforms were fabricated by the replica method using a polyurethane foam and an Al₂O₃-ND slurry with various ND contents (0, 1, 3, and 10 vol%). The preforms were sintered at 1500 °C for 4 h under argon gas protection. Finally, the composites were fabricated by Al melt infiltration into the preforms via the squeeze casting method. The microstructure of the fabricated composites was analyzed using optical and scanning electron microscopes. The hardness of the composites was measured using a Vickers hardness tester. The results of the microstructural evaluations demonstrated a good distribution of ND in the preform. By increasing the ND content from 0 to 10 vol%, the matrix average grain size decreased from 143 μm to 76 μm. The results of the Vickers hardness test showed that increasing the volume percentage of ND increased the composite hardness to 263.8 Vickers at 10 vol%. The two main strengthening mechanisms for these composites are the Orowwn mechanism (volume fraction of ND particles) and the Hal-Petch mechanism (grain size), which affect the hardness behavior. https://jpst.irost.ir/article_1338_05311655a15b75fab86956663e1819cd.pdf