Magnetic-hardening studies and novel techniques for preparation of high-performance magnets. Final report, 1 Jan 90-25 Jan 92

Technical Report · Tue Apr 28 04:00:00 EDT 1992

OSTI ID:7039744

Hadjipanayis, G C

Our efforts in permanent magnets have been focused on the search for new phases and alloys with high magnetization, large anisotropy, and high Curie temperature that can be used for permanent magnet development and on the magnetic hardening behavior of R-FE-B magnets. The systems studied include Fe-Mo, Co-Zr-B and as-cast Nd(Pr)-rich alloys with coercivities exceeding 6 kOe obtained in the latter two samples. Small additions of Al and Cu have been found to increase the coercivity of melt-spun R-FE-B magnets substantially (by as much as 8 kOe). The microstructure of the substituted samples is more homogenous with the secondary Nd-AI(Cu)-rich phases uniformly distributed throughout the sample. In addition, disturbed lattice regions were observed at most of the grain boundaries. In Cu-substituted melt-spun samples several faults have been observed inside the 2:14:1 grains. This is the first time that defects were observed in a 2:14:1 matrix and they have been attributed to the small solubility of Cu on Fe. As-cast Nd(Pr)-Fe1-xMnx-B samples have been found to have large coercivities at cryogenic temperatures. The large coercivities observed are due to domain wall pinning at atomic-size defects caused by the random Mn site occupation (leading to sites with fluctuations in exchange and anisotropy) because of the extremely thin domain walls.

• Research Organization: Delaware Univ., Newark, DE (United States). Dept. of Physics and Astronomy
• OSTI ID: 7039744
• Report Number(s): AD-A-254761/0/XAB; CNN: DAAL03-90-G-0026
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102 -- Metals & Alloys-- Structure & Phase Studies
360104* -- Metals & Alloys-- Physical Properties
ALLOYS
ALUMINIUM
ANISOTROPY
BORON ALLOYS
COBALT ALLOYS
COERCIVE FORCE
COPPER
CRYOGENICS
CRYSTAL STRUCTURE
CURIE POINT
DOMAIN STRUCTURE
ELEMENTS
GRAIN BOUNDARIES
HARDENING
IRON ALLOYS
MAGNETIC PROPERTIES
MAGNETIZATION
MAGNETS
METALLURGICAL EFFECTS
METALS
MICROSTRUCTURE
MOLYBDENUM ALLOYS
PERMANENT MAGNETS
PHYSICAL PROPERTIES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENTS
TRANSITION TEMPERATURE
ZIRCONIUM ALLOYS