Fc-Pt-Nb permanent magnet with an ultra-high coercive force and a large maximum energy product, and method for producing the same

• US 4,863,530 A
• Filed: 12/01/1988
• Issued: 09/05/1989
• Est. Priority Date: 04/30/1987
• Status: Expired due to Term

• Current Assignee: The Foundation The Research Institute of Electric and Magnetic Alloys
• Original Assignee: The Foundation The Research Institute of Electric and Magnetic Alloys
• Inventors: Watanabe, Kiyoshi, Masumoto, deceased, Hakaru, Matushima, executor, by Hiroshi
• Primary Examiner(s): Sheehan, John P.
• Application Number:
  US07/278,346
• Time in Patent Office: 278 Days
• Field of Search: 148/101, 148/102, 148/103, 148/120, 148/121, 148/122
• US Class Current: 148/101
• CPC Class Codes: C21D 6/00 Heat treatment of ferrous alloys
• CPC Class Codes: C22C 30/00 Alloys containing less than 50% by weight of each constituent
• CPC Class Codes: C22F 1/14 of noble metals or alloys based thereon
• CPC Class Codes: H01F 1/04 metals or alloys

Abstract

The disclosed permanent magnet has a coercive force of larger than 500 Oe, a residual magnetic flux density of larger than 5 kG, and a maximum energy product of larger than 2 MGOe, and it consisting essentially of 48˜66.9 Atm % of iron, 33˜47 Atm % of platinum, and 0.1˜10 Atm % of niobium. It includes a crystal structure of an incomplete single γ1 phase of a face-centered tetragonal system due to either the composition thereof or heat treatment applied thereto. The permanent magnet are made by heating an alloy of the above main composition at 900°˜1,400° for one minute to ten hours and quenching the alloy at a high speed of faster than 30° C./minute but slower than 2,000° C./sec.

Claims

1. A method for producing a permanent magnet having a large maximum energy product and an ultra-high coercive force, said method comprising the steps of heating an alloy consisting essentially of 48 to 66.9 Atm E% of iron, 33 to 47 Atm % of platinum, 0.1 to 10 Atm % of niobium, and less than 0.5 Atm % of impurities at 900 to 1,400°

C. for one minute to ten hours so as to apply a homogenizing solid solution treatment thereto, and quenching the alloy at a high speed cooling rate of about 30°

C./minute to about 2,000°

C./second.

2. A method for producing a permanent magnet having a large maximum energy product and an ultra-high coercive force, said method comprising the steps of heating an alloy consisting essentially of 48 to 66.9 Atm% of iron, 33 to 47 Atm % of platinum, 0.1 to 66.9 Atm % of niobium, and less than 0.5 Atm % of impurities at 900 33 to 1,400°

C. for one minute to ten hours so as to apply a homogenizing solid solution treatment thereto, quenching the alloy at a high speed cooling rate of about 30°

C./minute to about 2,000°

C./second, reheating the alloy at 450 to 800°

C. for one minute to 500 hours, and cooling said reheated alloy.

3. A method for producing a permanent magnet having a large maximum energy product and an ultra-high coercive force, said method comprising the steps of heating an alloy consisting essentially of 48 to 66.9 Atm % of iron, 33 to 47 Atm % of platinum, 0.1 to 10 Atm % of niobium, and less than 0.5 Atm % of impurities at 900 to 1,400°

C. for one minute to then hours so as to apply a homogenizing solid solution treatment thereto, quenching the heated alloy at a high speed cooling rate of about 30°

C./minute to 2,000°

C./second, plastically working the quenched alloy at a reduction ratio of greater than 80%, reheating the worked alloy at 450 to 800°

C. for one minute to 500 hours, and cooling the worked alloy.

4. A method for producing a permanent magnet according to claim 3, wherein said plastic working consists of wire-drawing.

5. A method for producing a permanent magnet according to claim 3, wherein said plastic working consists of rolling.