Alloying in an immiscible Cu-Nb system upon solid-state reaction

Book · Tue Dec 31 04:00:00 EST 1996

OSTI ID:479285

Pan, F; Ling, Z F; Gao, K Y; Liu, B X ^[1]

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1. Tsinghua Univ., Beijing (China). Dept. of Materials Science and Engineering

In an immiscible Cu-Nb system, an amorphous alloy and two metastable crystalline phases were obtained by solid-state reaction of Cu-Nb multilayered films, and the formation of the alloy phases was found to be quite sensitive to the average composition of the films. At Nb concentration of 75 at%, amorphization was achieved by 250 C annealing for 50 min, while in the films with compositions of 70 and 80 at% Nb, a simple cubic (a = 0.405 {+-} 0.005 nm) and an orthorhombic phase (a = 0.421, b = 0.334, and c = 0.291 {+-} 0.005 nm) were observed, respectively. Thermodynamic calculation was conducted for the Nb-Cu alloy phases and the energetic state of the multilayers, which consisted of 9 Cu/Nb bilayers. It turned out that the excess free energy originating from the interfacial atoms could raise the multilayers to an energy level being higher than that of the amorphous or/and metastable crystalline phases both with a convex shape, and thus provided a major driving force for alloy phase formation in such immiscible system.

• OSTI ID: 479285
• Report Number(s): CONF-951155--; ISBN 1-55899-301-0
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AMORPHOUS STATE
COPPER ALLOYS
CUBIC LATTICES
DIFFUSION
EXPERIMENTAL DATA
FREE ENERGY
HEAT TREATMENTS
INTERMETALLIC COMPOUNDS
NIOBIUM ALLOYS
ORTHORHOMBIC LATTICES
PHYSICAL VAPOR DEPOSITION
SYNTHESIS
THIN FILMS