Distinct atomic structures of the Ni-Nb metallic glasses formed by ion beam mixing

Journal Article · Sat Dec 15 00:00:00 EST 2007 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.2825407· OSTI ID:21057562

Tai, K P; Wang, L T; Liu, B X ^[1]

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1. Advanced Materials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

Four Ni-Nb metallic glasses are obtained by ion beam mixing and their compositions are measured to be Ni{sub 77}Nb{sub 23}, Ni{sub 55}Nb{sub 45}, Ni{sub 31}Nb{sub 69}, and Ni{sub 15}Nb{sub 85}, respectively, suggesting that a composition range of 23-85 at. % of Nb is favored for metallic glass formation in the Ni-Nb system. Interestingly, diffraction analyses show that the structure of the Nb-based Ni{sub 31}Nb{sub 69} metallic glass is distinctly different from the structure of the Nb-based Ni{sub 15}Nb{sub 85} metallic glass, as the respective amorphous halos are located at 2{theta}{approx_equal}38 and 39 deg. To explore an atomic scale description of the Ni-Nb metallic glasses, an n-body Ni-Nb potential is first constructed with an aid of the ab initio calculations and then applied to perform the molecular dynamics simulation. Simulation results determine not only the intrinsic glass forming range of the Ni-Nb system to be within 20-85 at. % of Nb, but also the exact atomic positions in the Ni-Nb metallic glasses. Through a statistical analysis of the determined atomic positions, a new dominant local packing unit is found in the Ni{sub 15}Nb{sub 85} metallic glass, i.e., an icositetrahedron with a coordination number to be around 14, while in Ni{sub 31}Nb{sub 69} metallic glasses, the dominant local packing unit is an icosahedron with a coordination number to be around 12, which has been reported for the other metallic glasses. In fact, with increasing the irradiation dose, the Ni{sub 31}Nb{sub 69} metallic glasses are formed through an intermediate state of face-centered-cubic-solid solution, whereas the Ni{sub 15}Nb{sub 85} metallic glass is through an intermediate state of body-centered-cubic-solid solution, suggesting that the structures of the constituent metals play an important role in governing the structural characteristics of the resultant metallic glasses.

• OSTI ID: 21057562
• Journal Information: Journal of Applied Physics, Vol. 102, Issue 12; Other Information: DOI: 10.1063/1.2825407; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AMORPHOUS STATE
BCC LATTICES
COORDINATION NUMBER
EMISSION SPECTRA
FCC LATTICES
INTERMEDIATE STATE
INTERMETALLIC COMPOUNDS
ION BEAMS
METALLIC GLASSES
MOLECULAR DYNAMICS METHOD
NICKEL ALLOYS
NIOBIUM ALLOYS
RADIATION DOSES
SIMULATION
SOLID SOLUTIONS
TRANSMISSION ELECTRON MICROSCOPY
VITRIFICATION
X-RAY DIFFRACTION
X-RAY SPECTRA