The effect of aging treatment on magntic properties of alnico permanent magnet alloys

Dissertant

Husayn, Abbas Khammas

University

University of Technology

Faculty

-

Department

Department of Production Engineering and Metallurgy

University Country

Iraq

Degree

Master

Degree Date

2000

English Abstract

Alnico-8 magnetic alloy was prepared using high purity materials (99.99 %, Co 99.95 % Ni, 99.961 % Cu, Aramco Iron (99.98 %Fe), 99.89 Al and ferrotitanium) in high frequency induction furnace. The alloy was then given thermomagnetic treatment at 1250°C then cooling in a magnetic field (3500 oe) for 5-7 min followed by a sequential aging at 650 and 550°C for different period of time. Changes in magnetic properties and mechanical hardness due to spinodal decomposition (a ⟶ a1 + a2) of the Alnico-8 alloy were examined under the influence of different heat treatment compared to that of the as-cast alloy.

The optimum magnetic properties [Hc= 80.3 KA / m, HcJ = 85.4 KA / m, Br = 0.8T, (BH) max = 22.4 KJ / m3, Edemag-32.12 KJ / mr = 4.01 and x =3.01], of Alnico-8 alloy were obtained after aging at 650 and 550°C for 48 hrs.

But the (BH) max is lower than the standard value (42KJ / m3). The other part of this work is to study the reason that lead to poor magnetic properties of Alnico-5 alloy which was prepared in the same procedure used for Alnico-8. A study of low magnetic properties [Hc= 14.6 KA / m, HcJ = 15.0 KA / m, B=0.582T and (BH) max2.3 KJ / m3) in the Alnico-5 has shown that two distinct reasons are responsible for decreasing in a magnetic properties, the first is the existence of the y -phase parasitic precipitation and the other is inhomogeneousity in alloy.

Also the results indicate the absence of controlled cooling rate and controlled magnetic annealing systems in thermomagnetic furnace have a great effect on the final magnetic properties.

Main Subjects

Materials Science , Minerals

Topics

• Mechanical properties
• Magnetic properties
• Alnicos

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-306199