Microstructural evolution and mechanical properties of an ultrahigh-strength Al−Zn−Mg−Cu alloy via powder metallurgy and hot extrusion
01 Apr 2021-Journal of Central South University (Central South University)-Vol. 28, Iss: 4, pp 1195-1205
TL;DR: In this article, a novel ultrahigh-strength Al−10Zn−3.5Mg−1.5Cu alloy was fabricated by powder metallurgy followed by hot extrusion.
Abstract: In this work, a novel ultrahigh-strength Al−10Zn−3.5Mg−1.5Cu alloy was fabricated by powder metallurgy followed by hot extrusion. Investigations on microstructural evolution and mechanical properties of the fabricated samples were carried out. The results show that the grain size of sintered samples matches with the powder particles after ball milling. The relative densities of sintered and hot extruded samples reach 99.1% and 100%, respectively. Owing to the comprehensive mechanism of grain refinement, aging and dispersion strengthening, the ultimate tensile strength, yield strength and elongation of the Al−10Zn−3.5Mg−1.5Cu alloy after hot extrusion and subsequent heat treatment achieve 810 MPa, 770 MPa and 8%, respectively.
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TL;DR: In this article , in-situ TiB2/AlSi7Mg composites were successfully fabricated using powder metallurgy and hot extrusion, and the results showed that the formation of fine grains and homogeneous subspherical silicon particles in as-extruded composites with high ductility (elongation of 21.7%) is achieved by perfect metallurgical bonding during severe plastic deformation.
Abstract: In this work, in-situ TiB2/AlSi7Mg composites were successfully fabricated using TiB2 decorated AlSi7Mg alloy powder synthesized via salt-metal reaction and gas atomization, followed by powder metallurgy and hot extrusion. Microstructure and mechanical properties were investigated by optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) and tensile tests. The results show that the formation of fine grains and homogeneous subspherical silicon particles in as-extruded composites with high ductility (elongation of 21.7%) is achieved by perfect metallurgical bonding during severe plastic deformation. The covering effect of TiB2 aggregates around silicon particles as particle shells has hindered the dissolution of silicon in the composite. After T6 treatment, the ultimate strength, yield strength and elongation at fracture of the 2 wt% TiB2/AlSi7Mg composite reach up to 344 MPa, 298 MPa and 8.6%, respectively. The excellent mechanical properties are mainly attributed to grain refinement, silicon optimization and precipitation strengthening. This study provides a good solution for improving the strength and toughness of Al–Si alloy.
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