Glass Structure Control of Zr-TM-Al (TM: Cu, Ni and Co) BGAs with Small Additive Elements

The degree of amorphousness of the cast glassy sample is evaluated by free volume, which can be roughly estimated by density. The glass structural difference of cast glassy samples is mainly originated to the difference of those cooling rates. In order to clarify the degree of amorphousness, we use the volume change during annealing just below glass transition temperature (Tg) in this study. Therefore the volume change has close relation with free volume. We tried to control the excess free volume in Zr-TM-Al (TM: Cu, Ni and Co) bulk glassy alloys (BGAs) using small additive element. We found the elements; Pd, Ag, Pt and Au, whose outer d-electrons are filled up, are effective to increase the volume change/free volume in Zr-Cu-Al BGAs. The relationship between the Young’s modulus and volume change indicates the existence of two groups. The difference between them might be originated to the difference in glass structures.