Metastable bcc mischmetal-magnesium alloys

Technical Report · Wed Feb 01 04:00:00 EST 1989

OSTI ID:6507439

Sabariz, A L.R.

The bcc phase in the MM-Mg system can be metastably retained at room temperature for magnesium composition within the range 16 at.% - 20 at.%. The retention of a lower composition was restricted by quenching rate and at higher concentrations by intermetallic compound precipitation. The lattice parameter for the pure bcc mischmetal phase was determined by extrapolation. The value obtained (a/sub E/ = 4.131 /angstrom/) was in good agreement with the theoretical value (a/sub t/ = 4.156 /angstrom/). Magnetic susceptibility data suggested that bcc mischmetal-magnesium alloys underwent a change from paramagnetic to antiferromagnetic behavior on cooling at /approximately/20 K, independent of magnesium composition. The value found for the magnetic effective moment per gram-atom-magnetic-rare earth of each bcc MM-Mg alloy examined (MM - 16 Mg, MM - 18 Mg and MM - 20 Mg) was found to be constant (p/sub eff/ approx. 1.62 ..mu../sub B/), independent of the magnesium composition. The observed Curie-Weiss temperature values decreasing with the magnesium content increasing were due to magnetic dilution. The equilibrium reaction bcc ..-->.. dhcp + MMMg presented an undercooling effect of /approximately/40/degree/C around the eutectoid composition (/approximately/17 at.% Mg). The sluggish character of this reaction was considered the strongest effect for the bcc structure retention in the mischmetal-magnesium system. 16 refs., 27 figs.

• Research Organization: Ames Lab., IA (USA)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6507439
• Report Number(s): IS-T-1392; ON: DE89007568
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ALLOYS
COHERENT SCATTERING
CRYSTAL STRUCTURE
CURIE-WEISS LAW
DIFFRACTION
ENERGY LEVELS
EXCITED STATES
MAGNESIUM ALLOYS
MAGNETIC PROPERTIES
MAGNETIC SUSCEPTIBILITY
METASTABLE STATES
MICROSTRUCTURE
PHYSICAL PROPERTIES
SCATTERING
TEMPERATURE DEPENDENCE
X-RAY DIFFRACTION