Claims
- 1. Acicular alloy base magnetic powder particles comprising nickel, iron and cobalt having an average particle long axis size of not larger than 0.20 .mu.m, such that a ratio of a half-width of an anisotropic magnetic field distribution to a coercive force is not larger than 3.2, an axial ratio of from 4 to 8, a cobalt content of from 5 to 50% by weight based on the weight of iron, a nickel content in an amount of at least 2% by weight based on the weight of iron and a saturation magnetization of at least 120 emu/g after being kept standing at a temperature of 60.degree. C. and relative humidity of 90% for a week, particle surfaces of which are covered with a ferrite film comprising iron and cobalt and further including a film comprising at lest one of aluminum and silicon.
- 2. The acicular alloy base magnetic powder according to claim 1, wherein the ferrite film has a thickness of 5 to 30 .ANG..
- 3. The acicular alloy base magnetic powder according to claim 1, wherein the content of cobalt is from 10 to 30% by weight based on the weight of iron.
- 4. The acicular alloy base magnetic powder particles according to claim 1, wherein nickel is locally present in surface parts of said alloy particles.
- 5. The acicular alloy base magnetic powder particles according to claim 1, wherein nickel is present in said alloy particles in the form of a solid solution of iron and nickel.
- 6. The acicular alloy base magnetic powder according to claim 1, wherein a coated amount of at least one of silicon and aluminum is from 1 to 9 atoms/nm.sup.2.
Priority Claims (5)
Number |
Date |
Country |
Kind |
63-275827 |
Oct 1988 |
JPX |
|
1-27263 |
Feb 1989 |
JPX |
|
1-68754 |
Mar 1989 |
JPX |
|
1-92437 |
Apr 1989 |
JPX |
|
1-96697 |
Apr 1989 |
JPX |
|
Parent Case Info
This application is a divisional of copending application Ser. No. 07/429,642, filed on Oct. 31, 1989, now abandoned, the entire contents of which are hereby incorporated by reference.
US Referenced Citations (12)
Foreign Referenced Citations (3)
Number |
Date |
Country |
63-064306 |
Mar 1988 |
JPX |
63-184307 |
Jul 1988 |
JPX |
63-184308 |
Jul 1988 |
JPX |
Divisions (1)
|
Number |
Date |
Country |
Parent |
429642 |
Oct 1989 |
|