Fabrication of bulk glassy Zr55Al10Ni5Cu30 alloy of 30 mm in diameter by a suction casting methodQ

A bulk glassy Zr55Al10Ni5Cu30 alloy in a cylindrical form with a diameter of 30 mm and a length of 50 mm was produced by sucking the molten alloy into a copper mold. The sucking force was generated from the rapid movement (5.0 m/s) of piston with a diameter of 30 mm which was set at the center of the copper hearth. The sucking velocity is evaluated to be as high as 22.1 kg/s. Neither cavity nor hole is seen in the transverse cross section of the bulk glassy alloy. The glass transition temperature (T-g), crystallization temperature (T-x) and supercooled liquid region defined by Delta T-x(=T-x-T-g) are nearly the same as those for the melt-spun glassy ribbon with a thickness of 30 mu m, in spite of the significant difference in sample thickness by three orders. Furthermore, there is no appreciable difference in T-g, T-x and Delta T-x over the whole cast sample. The Vickers hardness number is 523, in agreement with that (=510) for the corresponding melt-spun glassy ribbon and cast bulk glassy cylinders with diameters below 15 nm. Thus, the direct production of the bulk glassy alloy with a diameter of 30 mm by the suction casting method is important for the future development of bulk glassy alloys.