M. Phil. Physics

1. Alnico
AAMIR SALEEM
F20BPHYS3E01029

2. Key Concepts
 What is Alnico
 Alnico Magnetism
 Alnico Composition
 Types of Alnico
 Development of Alnico
 Preparation of Alnico
 Properties of Alnico
 Uses of Alnico

3. Alnico
Alnico is the name for an iron alloy that
primarily consists of
iron, aluminum (Al), nickel (Ni)
and cobalt (Co). That is why it is called al-ni-
co. It can also be spelled AlNiCo.
Sometimes, it may also
contain copper and titanium. Alnico alloys are
used as permanent magnets, as they are
ferromagnetic.

4. Alnico Magnetism
Alnico alloys were considered to be the strongest
kind of magnets before rare earth magnets were
developed in the 1970s. Alnico alloys have
ferromagnetic properties which makes it strong
permanent magnets. They are listed as some of
the best permanent magnets for over fifty years
now. Alnico alloys can also be magnetized to
create strong magnetic fields. These magnets also
show excellent stability in a wide range of
temperature. Alnico magnets can be effective in
temperature up to 1000°F.

5. Alnico Composition
The general composition of Alnico alloys is Al- 8-12%,
Ni- 15-26%, and Co- 5-24%. It may also contain up to
6% copper (Cu), and up to 1% titanium (Ti). Depending
on the percentage of the different components, there
can be various different types of Alnico alloys.

6. Types od Alnico
Based on the process of preparation, and the different
uses, alnico alloys can be classified into three main types.
1 . Cast Alnico
2 . Sintered Alnico
3 . Bar Alnico

7. Development of Alnico
The development of Alnico began in Japan in 1931. T.
Mishima was the first person to discover an alloy of
aluminum, nickel and cobalt that had high ferromagnetism.
The first Alnico alloy had ferromagnetism of 400 Oe
(oersted- unit for magnetizing field). It was the double of
the magnetic field strength of the best magnet steels in
existence at the time.

8. Preparation of Alnico
Generally, Alnico magnets are prepared in the metallurgic pressing-
sintering process or casting process. The right heat treatment is very
important in the process of the preparation of Alnico for the product to
have the desired magnetic properties. If the applied heat is not right, the
product will have the coercivity equal to that of iron, which is 10 Oe.
The process of preparing the Alnico alloys consists of heating at a critical
temperature, and then cooling in the presence of a strong magnetic field.
First, all the raw materials are mixed together before the heating process
starts. After the iron, aluminum, nickel, cobalt, and all the other
components have been added in the right proportions, a liquefier is added.
An external magnetic field is applied to it to orient the Alnico’s anisotropy
in the desired magnetic axis. It is done during the precipitate particle
nucleation (during cooling down from 900 °C to 800 °C).

9. Properties of Alnico
All Alnico alloys have strong magnetic properties and high ferromagnetism.
Alnico alloys are the only magnets to have useful magnetic powers at red hot
temperature (500°C – 800°C).
Alnico magnets have some of the highest curie points among all the magnetic
materials. It ranges around 800°C.
Unlike ceramic magnets, Alnico magnets have the property of electric
conductivity.
Alnico alloys have very good resistance to corrosion.
Some Alnico alloys can have isotropic properties while others can have
anisotropic properties.

10. Uses of Alnico
Alnico alloys are used as strong permanent magnets.
Alnico alloys can deliver good flux density at very economical prices.
Alnico alloys are used to manufacture Microphones, electric guitar pickups, electric motors,
loudspeakers, travelling-wave tubes, Hall Effect sensors etc.
Alnico speakers are the favorite of many musicians as they are known to produce the best
tone, and they also respond quickly. Alnico speakers are the best for jazz, blues, and mellow
rock.
Alnico speakers are the favorite of many musicians as they are known to produce the best
tone, and they also respond quickly. Alnico speakers are the best for jazz, blues, and mellow
rock.
Because of their high magnetic properties, Alnico alloys have many important uses in
industrial functioning. From electric motors to guitar pickups to cow magnets – alnico alloys
have diverse usefulness. Alnico magnets are the reliable answer whenever strong
permanent magnets are needed.