bcc transition metals under pressure: results from ultrasonic interferometry and diamond-cell experiments. [Nb--Mo, Ta--W]

Conference · Thu Jan 01 04:00:00 EST 1976

OSTI ID:7317845

Katahara, K W; Manghnani, M H; Ming, L C; Fisher, E S

Hydrostatic pressure derivatives of the single-crystal elastic moduli, dC/sub ij//dP, have been measured ultrasonically for b.c.c. Nb--Mo and Ta--W solid solutions. The composition dependence of various electronic properties of these alloys is known to be reasonably well approximated by a rigid-electron-band filling model where e/a, the electron per atom ratio, is the primary parameter. The results indicate that the elastic moduli and their pressure derivatives may also be calculated in such a model. In particular, the dC/sub ij//dP show relatively sharp increases at e/a compositions of 5.4 for Nb--Mo and 5.7 for Ta--W. Both compositions correspond to changes in Fermi surface topology, as deduced from existing band calculations and the rigid band assumption. The results are discussed in the light of related electronic properties and possible geophysical applications. A comparison is also made between ultrasonic results and X-ray diffraction data for Nb. Using diamond-anvil pressure cell, compression of Nb was determined by X-ray diffraction up to 55 kbar in a liquid medium under purely hydrostatic conditions, and up to 175 kbar in a solid medium under nonhydrostatic conditions. The data obtained under hydrostatic conditions agree well with the ultrasonic equation of state and shock wave data, whereas the nonhydrostatic results tend to imply either a higher bulk modulus K/sub s/ or a higher (par. deltaK/sub s//par. deltaP)/sub T/.

• Research Organization: Argonne National Lab., IL (USA)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 7317845
• Report Number(s): CONF-760716-4
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ALLOY SYSTEMS
ALLOYS
BINARY ALLOY SYSTEMS
ELASTICITY
MECHANICAL PROPERTIES
MOLYBDENUM ALLOYS
NIOBIUM ALLOYS
PHYSICAL PROPERTIES
PRESSURE DEPENDENCE
TANTALUM ALLOYS
TENSILE PROPERTIES
THERMODYNAMIC PROPERTIES
TUNGSTEN ALLOYS