FABRICATION OF BULKY ZR-BASED GLASSY ALLOYS BY SUCTION CASTING INTO COPPER MOLD

Bulk glassy Zr55Al10Ni5Cu30 alloys in a cylindrical form with a diameter up to 16 mm and a length of 70 mm were 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 16 mm which was set at the center of the copper mold. The sucking velocity was evaluated to be as high as 6.3 kg/s. Neither cavity nor hole is seen on the outer surface of the bulk glassy alloy and the glass transition temperature (T-g), crystallization temperature (T-x) and supercooled liquid region defined by Delta T-x(=T-x-T-g) are the same as those for the melt-spun glassy ribbon with a thickness of about 30 mu m. Furthermore, there is no appreciable difference in T-g, T-x and Delta T-x over the whole cast sample. The tensile fracture strength is 1620 MPa which is comparable to the compressive strength. The fracture takes place along the maximum shear plane and the size of the Veins is about ten times as large as that for the melt-spun glassy ribbon. The significant difference indicates that the deformation for the cast bulk alloy takes place over the thicker and wider region. Thus, the direct production of the bulk glassy alloy with good deformability by the suction casting method is important for the future development of bulk glassy alloys.