Abstract
The main purpose of this paper is to investigate the crystallization process and the change in mechanical properties with the crystallization of Ni-Zr and Ni-B amorphous alloys. The amorphous specimens, whose compositions were around the eutectic composition, were obtained by a rapid quenching method. The specimens were heated to crystallize up to a temperature of 50 K above Tx for 1.8 ks. The following results were obtained.
(1) Crystallization temperatures Tx of Ni-Zr and Ni-B amorphous alloys are highest at the composition of the eutectic point, and the activation energies of crystallization are also largest at the eutectic composition.
(2) The hardness of the specimen in amorphous state was larger than that of mother alloy in the crystalline state. The hardness of the crystallized specimen by heating was larger than that in amorphous state.
(3) The tensile strength of the specimen in amorphous state was larger than that of crystallized specimen. The specimens in amorphous state were very flexible and tough, but the specimens became brittle with crystallization.
(4) Young’s moduli of the amorphous specimens obtained by the measurement of bending moment-curvature relation were almost the same as those by other methods. Young’s modulus of the amorphous specimen at the eutectic composition was smaller than those of other compositions, indicating that the Young’s modulus is the smaller for the stable amorphous structure.
