On a New Magnet Alloy “Malcolloy” in the System of Cobalt and Aluminum

Abstract

Magnetic properties of ferromagnetic Co-Al alloys containing 4.32∼24.90% alminum have been measured. It has been found that the alloys containing more than about 10% aluminum shows high coercive forces when temperedat 500∼550°C after water-quenching from 1380°C (non-magnetic β′ phase): The 15.02% aluminum alloy showing the highest coercive force has a residual magnetic flux density of 4,200 G, a coercive force of 1200 Oe and a maximum energy product of 1.71×106 G·Oe. Thus the present investigators have named these alloys “Malcolloy” which is an abbreviation of the magnetic Al-Co alloy. These alloys having high coercive forces consist of many ferromagnetic elongated particles about 300∼1000 Å in mean diameter dispersed in the matrix of the non-magnetic β′ phase and consequently it may be concluded that the high coercivity of the alloys is probably caused by the existence of these small particles, each of them being composed of a single magnetic domain.