TY - JOUR
T1 - Structural instability of metallic glasses under radio-frequency-ultrasonic perturbation and its correlation with glass-to-crystal transition of less-stable metallic glasses
AU - Ichitsubo, T.
AU - Matsubara, E.
AU - Chen, H. S.
AU - Saida, J.
AU - Yamamoto, T.
AU - Nishiyama, Nobuyuki
N1 - Funding Information:
This work was supported by Grant-in-Aid for Scientific Research on the Priority Area Investigation of “Materials Science of Bulk Metallic Glasses” from the Ministry of Education, Science, Sports and Culture, Japan. One of the authors (T.I.) is very grateful to Kazuhiro Anazawa for his experimental support.
PY - 2006
Y1 - 2006
N2 - It has been reported that the structural stability is significantly deteriorated under radio-frequency-ultrasonic perturbation at relatively low temperatures, e.g., near/below the glass transition temperature Tg, even for thermally stable metallic glasses. Here, we consider an underlying mechanism of the ultrasound-induced instability, i.e., crystallization, of a glass structure to grasp the nature of the glass-to-liquid transition of metallic glasses. Mechanical spectroscopy analysis indicates that the instability is caused by atomic motions resonant with the dynamic ultrasonic-strain field, i.e., atomic jumps associated with the Β relaxation that is usually observed for low frequencies of the order of 1 Hz at temperatures far below Tg. Such atomic motions at temperatures lower than the so-called kinetic freezing temperature Tg originate from relatively weakly bonded (and/or low-density) regions in a nanoscale inhomogeneous microstructure of glass, which can be straightforwardly inferred from a partially crystallized microstructure obtained by annealing of a Pd-based metallic glass just below Tg under ultrasonic perturbation. According to this nanoscale inhomogeneity concept, we can reasonably understand an intriguing characteristic feature of less-stable metallic glasses (fabricated only by rapid melt quenching) that the crystallization precedes the glass transition upon standard heating but the glass transition is observable at extremely high rates. Namely, in such less-stable metallic glasses, atomic motions are considerably active at some local regions even below the kinetic freezing temperature. Thus, the glass-to-crystal transition of less-stable metallic glasses is, in part, explained with the present nanoscale inhomogeneity concept.
AB - It has been reported that the structural stability is significantly deteriorated under radio-frequency-ultrasonic perturbation at relatively low temperatures, e.g., near/below the glass transition temperature Tg, even for thermally stable metallic glasses. Here, we consider an underlying mechanism of the ultrasound-induced instability, i.e., crystallization, of a glass structure to grasp the nature of the glass-to-liquid transition of metallic glasses. Mechanical spectroscopy analysis indicates that the instability is caused by atomic motions resonant with the dynamic ultrasonic-strain field, i.e., atomic jumps associated with the Β relaxation that is usually observed for low frequencies of the order of 1 Hz at temperatures far below Tg. Such atomic motions at temperatures lower than the so-called kinetic freezing temperature Tg originate from relatively weakly bonded (and/or low-density) regions in a nanoscale inhomogeneous microstructure of glass, which can be straightforwardly inferred from a partially crystallized microstructure obtained by annealing of a Pd-based metallic glass just below Tg under ultrasonic perturbation. According to this nanoscale inhomogeneity concept, we can reasonably understand an intriguing characteristic feature of less-stable metallic glasses (fabricated only by rapid melt quenching) that the crystallization precedes the glass transition upon standard heating but the glass transition is observable at extremely high rates. Namely, in such less-stable metallic glasses, atomic motions are considerably active at some local regions even below the kinetic freezing temperature. Thus, the glass-to-crystal transition of less-stable metallic glasses is, in part, explained with the present nanoscale inhomogeneity concept.
UR - http://www.scopus.com/inward/record.url?scp=33750191939&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33750191939&partnerID=8YFLogxK
U2 - 10.1063/1.2346672
DO - 10.1063/1.2346672
M3 - Article
AN - SCOPUS:33750191939
VL - 125
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
SN - 0021-9606
IS - 15
M1 - 154502
ER -