Nanostructured bulk glassy Cu₆₀Zr₃₀Ti₁₀ alloy with high strength and good ductility in cast state

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ÂÛÎÄ×÷Õߣº³ÂÑÕÌà ÕÅÌÎ ÕÅΰ INOUE Akihisa ¶¡Çì·á

ÎÄÕÂÒ³Â룺1025 - 1029

Key words£ºbulk glassy Cu₆₀Zr₃₀Ti₁₀ alloy; casting; microstructure; nanocrystalline phase; mechanical property

Abstract: The bulk glassy Cu₆₀Zr₃₀Ti₁₀ alloy with a diameter up to 4mm and a length of 70mm containing nanocrystalline phase was successfully developed by using copper mold casting method. The temperature interval of the supercooled liquid region before crystallization is above 37K. The glass transition temperature (T_g) and the reduced glass transition temperature (T_g/T_l) of the cast bulk glassy Cu₆₀Zr₃₀Ti₁₀ alloy are 713K and 0.62. The cast bulk glassy alloy, which has high glassy forming ability, shows expected mechanical properties. The elastic modulus, yield strength, fracture strength and elongation including elastic elongation are 114GPa, 1785MPa, 2150MPa and 3.3% respectively in compressive deformation, and 112GPa, 1780MPa,2000MPa and 1.9% respectively in tensile deformation. High resolution transmission electron microscope (HRTEM) and nano-beam electron diffraction (NBED) studies indicate that the cast metallic bulk glassy Cu₆₀Zr₃₀Ti₁₀ alloy consists of nanocrystals with a size of -4nm embedded in glassy matrix. The nanoparticle is identified as CuZr and has point space group symmetry of pm3^-mª«and its lattice parameter is a=0.3262nm . The nanocrystalline phase grew up to 10nm upon annealing at 430¡æ for 10min and caused the alloy brittle.