Alnico magnets are made from aluminum, nickel, cobalt and other materials. They can be either cast or sintered. Cast Alnico is made by melting, heat treating, cooling and then grounding to specific tolerances and finally magnetizing. Sintered Alnico is made from a powdered mixture of materials and sintered and then cooled either within a magnetic field or without. Both cast and sintered Alnico can work for very high temperature up to 600ºC and are more hard and brittle.