Formation, Thermal Stability, and Mechanical Properties of Glassy Zr<SUB>60</SUB>Al<SUB>10</SUB>Ni<SUB>10</SUB>Cu<SUB>20</SUB> Alloy Rods with Diameters of 18 and 20 mm

Abstract

Bulk glassy alloy rods of diameters 18 and 20mm were formed during the tiltcasting of Zr 60 Al 10 Ni 10 Cu 20 . A further increase in the rod diameter to 22 mm resulted in the formation of a mixed structure with approximately 60 vol% glassy phase and 40 vol% crystalline phase, which comprised the central region of the transverse cross-section of the alloy rod. The glass transition temperature (Tg), onset temperature of crystallization (T x ), and liquidus temperature (T 1 ) were measured to be 666 K, 768 K, and 1153K, respectively, and the resultant ΔT x (= T x - Tg), Tg/T 1 , and γ (= T x /(Tg + T 1 )) values were 102 K, 0.578, and 0.422, respectively. The high glass-forming ability of supercooled liquids is attributed to the high resistance of the liquids against crystallization due to the large ΔT x . and high Tg/T 1 and γ values. For the alloy rod of diameter 20 mm, the Young's modulus, yield strength, elastic strain, and plastic strain under a uniaxial compressive load are 80 GPa, 1820 MPa, 0.022, and 0.060, respectively; the plastic strain of the rod with diameter 20 mm is greater than that (0.04) of the glassy alloy rod of diameter 2 mm, although there exist no appreciable differences between their strength levels and fracture behaviors. The success of formation of the large-sized Zr-based bulk glassy alloy rod, which exhibits large plastic strains in conjunction with high strength levels, is promising with regard to further extension of the applications of such highly functional materials.