Coercive force and microstructure in a Zr permalloy
An alloy containing 80.0% Ni, 12.65% Fe, 8.74% Mo, 0.36% Zr, and 0.25% Mn by weight was cast, homogenized, and successively cold rolled into thin strips with area reductions of 0, 50, 75, and 90%. Annealed samples were studied by optical and electron microscopy, electron diffraction, and magnetic testing to determine the effects of cold work and annealing on the microstructure and magnetic properties of the alloy. Cold work produced a high initial hardness together with high coercive force. Recrystallization of the cold worked structures occurred upon annealing at 800 deg C and above and caused significant and parallel decreases in hardness and coercive force. The activation energy for recrystallization was found to be 80.5 kcal/g mole (337.0 kJ/g mole) for the 50, 75, and 90% cold worked specimens. After annealing at 600 deg C, a small number of spherical Ni/sub 4/Mo particles were observed, but the particles produced little change in magnetic properties apparently because of their relatively coarse size and large spacing. Beginning at 700 deg C ribbon-shaped particles of a Ni/sub 5/Zr intermetallic compound also precipitated out of solid solution. Both the Ni/sub 4/Mo and Ni/sub 4/Zr precipitates were the result of a homogeneous continuous precipitation reaction within the grains. A peak in coercive force at 800 deg C is attributed to domain wall pinning associated with the fine distribution of rodlike Ni/sub 5/Zr particles. Cold working 90% and aging at 800 deg C was found to increase coercive force by almost 60% from the minimum produced by complete recrystallization. Annealing, however, decreased hysteresis and improved squareness. (auth)
- Research Organization:
- Western Electric Co., Inc., Baltimore
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-29-024745
- OSTI ID:
- 4330287
- Journal Information:
- Met. Trans., v. 5, no. 3, pp. 733-738, Other Information: Orig. Receipt Date: 30-JUN-74
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
Ceramics
& Other Materials-Metals & Alloys-Properties
Structure & Phase Studies
*PERMALLOY- MICROSTRUCTURE
*ZIRCONIUM ADDITIONS- MICROSTRUCTURE
ANNEALING
COLD WORKING
DOMAIN STRUCTURE
ELECTRON DIFFRACTION
ELECTRON MICROSCOPY
HARDNESS
HIGH TEMPERATURE
INTERMETALLIC COMPOUNDS
MAGNETIC FLUX
PRECIPITATION
RECRYSTALLIZATION