Primary Transformation Kinetics in Zr-Al-Ni-Cu-Pd Bulk Metallic Glass Correlated with Relaxation State
- PDF / 776,701 Bytes
- 6 Pages / 593.972 x 792 pts Page_size
- 7 Downloads / 248 Views
NTRODUCTION
BULK metallic glasses (BMGs) have attracted great interest in the field of materials science because of their unique fundamental properties as well as their application based on their good mechanical, chemical, and magnetic properties.[1–3] Especially, structural relaxation has been recognized as an important phenomenon, that originates from the glassy structure intrinsically.[4] The relaxation of BMGs occurs by low-temperature annealing around or below the glass transition temperature Tg and has been widely studied in terms of its effects on the local structure,[5,6] thermodynamics,[7–10] free volume kinetics,[11,12] and crystallization.[13,14] It is also well known that the relaxation state in BMGs significantly correlates to the ductility, which is a major concern for the applications of metallic glasses. Recently, the recovered ductility by appropriate annealing condition above Tg (so-called recovery annealing) has been reported in Zr-based BMGs.[15] The results are easily prospected in correlation with the structural relaxation in the glassy structure. Since BMGs in various relaxation states have to be used generally for industrial application due to different production methods, condition, morphology, and processing, it is still required to understand the relaxation behavior more in metallic glasses in both fundamental and applied fields. We have studied the effect of the production condition of chamber atmosphere on the structure and
properties of BMGs prepared by the Cu mold casting technique.[16] According to the previous studies, it is pointed out that the cooling effect changes with the atmosphere and is enhanced in Ar or He rather than in vacuum.[17] The results also enable us to produce BMGs in various relaxation states by controlling the chamber atmosphere. Actually, we have evaluated the relaxation state by the calorimetric measurement and clarified the influence of it on the compressive room-temperature ductility in Zr-Al-Ni-Cu(-Pd) BMGs.[18] Very recently, the authors have reported the preliminary study on the effect of relaxation state on the primary transformation (quasicrystallization) from the viewpoints of nucleation and grain growth behaviors.[19] The results obtained in this study exhibit the obvious change in the nucleation and grain growth rates of a quasicrystalline (QC) particle with the relaxation state of the glassy phase. In the current study, we intend to report the further investigation of primary transformation kinetics in the Zr65Al7.5Ni10Cu12.5Pd5 BMG in the various relaxation states. This study is expected to clarify the relationship between the relaxation state and the primary transformation in the glassy structure in detail. The results are believed to be quite useful for future applications of BMGs in the aspects of controlling the glassy structure in atomic level.
II. JUNJI SAIDA, Associate Professor, is with the Center for Interdisciplinary Research, Tohoku University, Aramaki, Aoba, Sendai 980-8578, Japan. Contact e-mail: [email protected] ALBERTUS D. SETYAWAN, Po
Data Loading...
