Alnico
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Alnico is a family of iron alloys which in addition to iron are composed primarily of aluminium (Al), nickel (Ni) and cobalt (Co), hence al-ni-co. Other elements present include copper, and sometimes titanium.
Contents
Composition
The composition of alnico alloys is typically 8–12% Al, 15–26% Ni, 5–24% Co, up to 6% Cu, up to 1% Ti, and the balance is Fe (30-40%).
Properties
Alnico alloys are ferromagnetic, with low coercivity-its resistance to loss of magnetism varies by grade from 630–1,880 oersteds (50–150 kA/m)-and it is used to make permanent magnets. Before the development of rare-earth magnets in the 1970s, they were the strongest type of permanent magnet.
Alnico alloys have some of the highest Curie temperatures of any magnetic material, around 800 °C, although the maximal working temperature is normally limited to around 538 °C. They are the only magnets that have useful magnetism even when heated red-hot.
Availability
Old type magents are all Alnico.
Safety and handling
Alnico contains nickel and cobalt which are know to be harmful.
