Structural characterization and consolidation of amorphous metals prepared by mechanical alloying

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:6110506

Boldrick, M S

Amorphous metals powders of Ni{sub x}Ti{sub 100{minus}x} (35 {le} x {le} 65), Ni{sub x} Zr{sub 100{minus}x} (35 {le} x {le} 74), Cu{sub 50}Ti{sub 50}, and Cu{sub 50}Zr{sub 50} were produced by mechanical alloying of the elemental powders, carried out under an argon atmosphere, in a SPEX high energy mixer/mill for 24 hours. Various parameters of the milling process, such as milling time, milling atmosphere, ball-to-powder weight ratio, and composition were studied for the Ni-Ti system. The alloyed powder was characterized using X-ray diffraction to determine if it was amorphous, electron microscopy to study the particle morphology, and differential thermal analysis to determine the glass transition and crystallization temperatures. The local atomic structure of the amorphous powders was characterized using x-ray and neutron diffraction. The amorphous structure of the mechanical alloys was found to be similar to that previously reported for rapidly quenched Ni{sub 35}Ti{sub 65}, Ni{sub 35}Zr{sub 65}, Cu{sub 50}Ti{sub 50}, and Cu{sub 50}Zr{sub 50}. Mechanically alloyed Ni{sub 50}Ti{sub 50} powder was vacuum compacted at pressures up to 250 ksi (1720 MPa) and temperatures up to 500{degree}C, the crystallization temperature. A maximum density of 89% of the theoretical value was obtained for a compact which was 9.5 mm in diameter and 1.5 mm thick. Electron microscopy was used to investigate the extent of plastic deformation and inter-article bonding. Vickers microhardness measurements on the compacts were plotted versus density and extrapolated to 100% density to obtain an estimate of 500 kg/mm{sup 2} for the room temperature hardness of the powder particles.

• Research Organization: California Univ., Los Angeles, CA (USA)
• OSTI ID: 6110506
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101 -- Metals & Alloys-- Preparation & Fabrication
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOY SYSTEMS
ALLOYS
AMORPHOUS STATE
BINARY ALLOY SYSTEMS
COHERENT SCATTERING
COPPER ALLOYS
DENSITY
DIFFRACTION
ELECTRON MICROSCOPY
ELECTRONIC STRUCTURE
HARDNESS
MECHANICAL PROPERTIES
METALLURGY
MICROHARDNESS
MICROSCOPY
NICKEL ALLOYS
PHYSICAL PROPERTIES
PLASTICITY
POWDER METALLURGY
POWDERS
SCATTERING
THERMAL ANALYSIS
THERMODYNAMIC PROPERTIES
TITANIUM ALLOYS
TRANSITION TEMPERATURE
VICKERS HARDNESS
X-RAY DIFFRACTION
ZIRCONIUM ALLOYS