Sub-Tg relaxation and multi-stage glass transition behavior for bulk glassy alloys

We have found for the first time the following three important relaxation phenomena for amorphous and bulk glassy alloys (BGAs), namely, (1) sub-Tg reversible enthalpy relaxation for multi-component amorphous alloys, (2) sub-Tg dynamic storage modulus transition and loss modulus peak for BGAs, and (3) two-stage storage modulus transitions and loss modulus peaks in the Tg and supercooled liquid (SL) region for BGAs. Although these phenomena were discovered around 1984 for the sub-Tg enthalpy relaxation and around 1991 for the sub-Tg dynamic modulus peak and the two-stage glass transitions, these results and concepts are important even at present as fundamental properties for deep understanding of BGAs. This review is expected to provide an opportunity to develop much useful BGAs with high glass-forming ability (GFA), wide SL region and high ductility.