Local structure in quasicrystal-forming Zr-based metallic glasses correlated with a stability of the supercooled liquid state

Abstract

Nanoquasicrystallization and the local structure of several Zr-based metallic glasses were investigated in correlation with a stability of the supercooled liquid state. Single icosahedral quasicrystalline phase (I-phase) formation is confirmed in the Zr70Al10Ni20 ternary and Zr70Cu30 binary metallic glasses with a high stability of the supercooled liquid state by the addition of a small amount of a noble metal such as 0.5–1at.% Pd or Au. Since the local structure does not change by nanoquasicrystallization as well as by the addition of 1at.% Pd in the Zr70Al10Ni20 ternary metallic glass on the basis of an extended X-ray absorption fine structure (EXAFS) study, we propose an icosahedral local structure in the quasicrystal-forming metallic glasses. No I-phase formation is observed in the Zr70Ni30 binary alloy by the addition of 1at.% Pd or Au, in which the stability of the supercooled liquid state is lower than those in the Zr70Cu30, Zr65Al7.5Cu27.5 and Zr70Al10Ni20 alloys. Since the tetragonal Zr2Ni-like local structure is identified in the Zr70Ni30 amorphous alloy, it is concluded that a strong correlation exists between the stability of the supercooled liquid state and the icosahedral local structure in the glassy state in Zr-based metallic glasses.