Hybrid nanostructured aluminum alloy with super-high strength

Abstract

Methods to strengthen aluminum alloys have been employed since the discovery of the age-hardening phenomenon in 1901. The upper strength limit of bulk Al alloys is ~0.7 GPa by conventional precipitation strengthening and increases to >1 GPa through grain refinement and amorphization. Here we report a bulk hybrid nanostructured Al alloy with high strength at both room temperature and elevated temperatures. In addition, based on high-resolution transmission electron microscopic observations and theoretical analysis, we attribute the strengthening mechanism to the composite effect of the high-strength nanocrystalline fcc-Al and nano-sized intermetallics as well as to the confinement effect between these nano phases. We also report the plastic deformation of nano-sized intermetallics and the occurrence of a high density of stacking faults and twins in fcc-Al after low-strain-rate deformation at room and high temperatures. Our findings may be beneficial for designing high-strength materials for advanced structural applications. An international team of scientists create an aluminum alloy that is twice as strong as those made by conventional techniques. Zhi Wang from IFW Dresden in Germany and Tohoku University in Japan and co-workers from China, Germany, Japan and Austria have developed a technique that allows the microstructure of aluminum alloys to be carefully controlled, enabling them to create hybrid structures consisting of nanoscale intermetallic compounds in an aluminum matrix. Previous attempts to create strong alloys included making an aluminum-based material that is non-crystalline, like glass, or one that is made up of crystalline nanograins. But these approaches lead to materials that are unsuitable for use at high temperatures. In contrast, the aluminum alloy created by the researchers exhibits high strength at both ambient and elevated temperatures. We report a bulk hybrid nanostructured Al alloy with super-high strength at both room and elevated temperatures. The strengthening mechanisms were clearly elucidated, which are mainly attributed to the composite structure and confinement effect between the nano phases. The confining effect can effectively suppress the premature brittle fracture of the nano-intermetallic phases. The microstructural strategy and strengthening mechanisms in this work may be beneficial for the scientific community in understanding and designing high-strength materials.