The Fabrication And Mechanical Properties Of Al₆₀Cu₂₀Ti₁₅Zr₅/Al Metallic Glass Composites By Hot-pressing Under High Pressure

The Al-based metallic glasses have great application potential for their highspecific strength and excellent corrosion resistance. However, the poor plasticity atroom temperature and low amorphous forming ability limit their use in practice.Therefore, it is urgent to find new ways to prepare Al-based amorphous and theircomposites with a large size. In this thesis, the Al₆₀Cu₂₀Ti₁₅Zr₅/Alamorphous powderswere prepared by ball-milling method. The Al-based amorphous composites reiforcedby pure Al were made by hot pressing method under high pressure. The influence ofpressing temperature on the microstructures and mechanical properties of theAl-based composites was studied. The main results are listed as follows:（1） The Al₆₀Cu₂₀Ti₁₅Zr₅/Alamorphous alloy powders can be obtained by ballmilling of element powders for120h on condition that the rotate speed was300rpmand ball-to-powder weight ratio is20:1. Either a faster rotate speed or a greaterball-to-powder weight ratio can shorten the time of amorphization. The size ofparticles decreased gradually and the shape became more regular during milling. Atlast, the powders turned into the approximatively circular particles with about10mmin diameters.（2） The bulk Al-based amorphous/Al composites were fabricated by hot-pressingunder high pressure （5GPa） and no crystallization of the glass metal occurred duringthe consolidation. The densification of the composites is strongly dependent on theconsolidation temperature and the content of pure Al. The desification of thecomposites increases with the rise of consolidation temperature and the content of Al.The highest densification appears in the composite containing60vol.%Al, whichreaches96%. The lowest densification is89%when consolidated at90°C. For thecomposites containing60vol.%Al, the densification is85%-89%.（3） The temperature and the content of pure Al have a n important impact on themechanical property of the bulk Al-based amorphous/Al composites. Roomtemperature compression tests reveal that the strength of the composites increaseswith the increase of the consolidation temperature. The composites consolidated at390°C exhibits the highest strength, and their yield strength and ultimate strength are307MPa and353MPa for the composite containing40vol.%Al, and255MPa and281MPa for the composites containing60vol.%Al, respectively. More addition of Aldecreases the strength but dramatically increases the plasticity of the samples consolidated at same temperature. The composites containing60vol.%Al exhibit verygood plasticity at room temperature. The compressive strength of the compositesobtained in the present work obeys the equal stress model.（4） The composites were annealed at480°C for10min. The amorphous matrixchanged into the nano-crystalline, which caused the increase of strength and thedecrease of plasticity remarkably.