US3989557A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process of producing semi-hard magnetic materials
Assignee: Fujitsu Ltd
•
Filing: 1975-07-03
•
Granted: 1976-11-02
•
Expires: 1995-07-03
Abstract
Abstract Semi-hard magnetic materials exhibiting an excellent square hysteresis loop are prepared by the following steps. An alloy material consisting essentially, by weight, of 73-93% Co, 1-5%Nb and the balance Fe is subjected to process annealing at not lower than 900 DEG C and cold working at a reduction of area of not less than 75% and then is subjected to any combination treatment involving one or more stress relief annealings at a temperature in the range 500 DEG -700 DEG C for a short period of time such that no intermetallic compound precipitates in said alloy followed by cooling to the ambient temperature, and one or more ageing treatments of said cooled material at a temperature in the range 600 DEG -900 DEG C for a considerably longer time such that an intermetallic compound does precipitate in said alloy.
Inventors
- 👤 Zenzo Henmi
- 👤 Tatsuji Sasaki
- 👤 Makoto Kassai
- 👤 Masanori Okada
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 16:03
CPC Classifications
C; C22; C22F; C22F1/00; C22F1/10; C22C; C22C19/00; C22C19/07; H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/04; H01H; H01H1/00; H01H1/02; H01H1/0201
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
149 words
A process of producing semi-hard magnetic materials having square hysteresis loop characteristics which comprises the steps of: process annealing an alloy material consisting, by weight, of 73 to 93% cobalt, 1 to 5% niobium and the balance consisting essentially of iron, at a temperature of not lower than 900° C, cold working said annealed alloy material at a reduction in area of not less than 75%; and thereafter subjecting said cold worked alloy material to a combination treatment including one or more stress-relief annealings at a temperature of 500° to 700° C for a period of time not longer than 10 minutes selected so that no intermetallic compound precipitates in said alloy material, and one or more additional aging steps at a temperature of 600° to 900° C for a period of time not shorter than 30 minutes selected so that an intermetallic compound precipitates in said alloy material.
Claim 2
Dependent Claim
149 words
A process of producing semi-hard magnetic materials having square hysteresis loop characteristics which comprises the steps of: process annealing an alloy material consisting, by weight, of 73 to 93% cobalt, 1 to 5% niobium and the balance consisting essentially of iron, at a temperature of not lower than 900° C, cold working said annealed alloy material at a reduction in area of not less than 75%; and thereafter subjecting said cold worked alloy material to a combination treatment including one or more stress-relief annealings at a temperature of 500° to 700° C for a period of time not longer than 10 minutes selected so that no intermetallic compound precipitates in said alloy material, and one or more additional aging steps at a temperature of 600° to 900° C for a period of time not shorter than 30 minutes selected so that an intermetallic compound precipitates in said alloy material.
Claim 3
Dependent Claim
17 words
The process according to claim 1 wherein said stress-relief annealed alloy is cooled to substantially ambient temperature.
Claim 4
Dependent Claim
29 words
A process according to claim 1 wherein said process annealing, said stress-relief annealing and said aging treatment are carried out in an atmosphere of non-oxidizing gas or in vacuum.
Claim 5
Dependent Claim
22 words
The process according to claim 1 wherein said stress-relief annealing is performed at a temperature within the range 600° to 650° C.
Claim 6
Dependent Claim
24 words
The process according to claim 3 wherein said stress-relief annealing is performed at a temperature within said range for a period of 5-10 minutes.
Claim 7
Dependent Claim
29 words
The process according to claim 1 wherein said stress-relief annealing is performed at a temperature of about 700° C for a period of time within the range 2-3 minutes.
Claim 8
Dependent Claim
32 words
The process according to claim 1 wherein said ageing step is performed at a temperature within the range 600° to 699° C during a period of time in excess of 1 hour.
Claim 9
Dependent Claim
31 words
The process according to claim 1 wherein said aging step is performed at a temperature within the range 751° to 900° C for a period of time less than 1 hour.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-11-02 | 1980-05-03 | 1980-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-11-02 | 1984-05-03 | 1984-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-11-02 | 1988-05-03 | 1988-11-02 | $7700.00 | Window Closed / Lapsed |