Microstructure characterization and mechanical properties of Al-matrix composites reinforced by artificially-cultured diatom frustules

Abstract

In this study, to enhance the understanding of characteristics and interaction of Al-SiO2 composites manufactured with hot extrusion, artificially-cultured diatom frustules (DFs) reinforced aluminum matrix composites have been manufactured by isostatic cool pressing and hot extrusion process. The effect of DFs content on composite particle characteristics, microstructures, phase distribution, fracture surfaces and mechanical properties of the hot-extruded composites were investigated in details. For hot-extruded Al-DFs composite samples, two typical morphologies of DFs were identified: (a) those with apparent matrix-DFs voids were formed by deformability inconsistency between matrix and reinforcement; (b) those with strong matrix-DFs interfacial integration originated from aggregated nano-sized DFs particles and potential reduction reaction between Al and SiO2. Uniform distribution of nano-sized DFs particles surrounding matrix grain boundaries significantly improved mechanical properties of Al-DFs composites. When DFs increased to 3 wt%, the fractography were transformed from dimple rupture of ductile failure into brittle-dominant fracture mode. Meanwhile, aluminum composites with 3 wt% DFs illustrated optimum tensile strength (185.2 MPa), yield strength (117.6 MPa) with elongation (13.5%), which exhibited strength increase of 20.7% and 32.0% respectively, compared with that of pure aluminum.

Keywords

• Aluminum-matrix composites (AMCs)
• Particle-reinforcement
• Mechanical properties
• Physical properties