Production of Zr55Cu30Ni5Al10 Glassy Alloy Rod of 30 mm in Diameter by a Cap-Cast Technique
used for the preparation of the master alloy. The purity of these metals; Zr(+Hf), Cu, Ni and Al were 99.99 mass%, 99.999 mass%, 99.99 mass% and 99.999 mass%, respectively. The alloy ingots were completely remelted, and cast into cylindrical rod samples with diameters from � 16 mm to � 30 mm by a modified cap-casting method, as shown in Fig. 1. The cap-cast technique was designed to obtain high cooling rate even at the upper part of cast specimen. The cast structure was examined by scanning electron microscopy (SEM), and the compositions of the quenched samples were determined with an electron probe microanalyzer (EPMA). The phase identification of the cast samples was performed by X-ray diffractometry. Oxygen concentration of the bulk glassy alloys was measured by a helium carrier fusioninfrared absorption. Microscopic cast structures were examined by transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM) using a JEOL 4000 FX. TEM samples were prepared by an electrolytic polishing machine using nitric methanol (30 vol% HNO3) at about 250 K.
Application of Zr-based bulk glassy alloys to golf clubs
Bulk glassy alloys have high tensile strength, while the Young's modulus is lower by 20 to 40% than those for the corresponding crystalline alloys. These unique mechanical properties are effective to increase the coefficient of restitution at the impact between a golf club and a golf ball. Bulk glassy alloys have in general been produced by the copper mold casting and die casting methods. We have developed a new manufacturing process for Zr-based bulk glassy alloys. By the use of the new process, we have succeeded in producing a glassy Zr-Al-Ni-Cu alloy in a shell shape with a dimension of about 90 x 40 mm and a thickness of 3 mm for glassy driver golf clubs. It exhibits excellent mechanical properties such as tensile strength of 1700MPa, Young's modulus of 81 GPa, and impact fracture toughness of 130 kJ/m 2 . These properties are suitable for the material for driver golf club heads. The glassy driver golf club with the shell shape in the impact region was confirmed to have a high coefficient of restitution.
Amorphous Al-based Thick Sheets Produced by Rapid Solidification of Supercooled Liquid Droplets
Des feuilles epaisses d'alliage amorphe Al 84 Ni 10 Mm 6 (Mm=mischmetal) ont ete elaborees par une technique de trempe en deux etapes consistant en une atomisation sous argon a haute pression suivie d'une solidification rapide par depot par choc des gouttelettes sur un cone rotatif en cuivre. L'etat amorphe, la morphologie et la durete des feuilles ainsi obtenues ont ete examines.