Interdependence of thermal aftereffect and natural aging in permanent magnet materials

The thermal aftereffect is proportional to the irreversible susceptibility and thus has a peak value in the zone of coercive force. It follows a logarithmic time law of the type whose constant shows a linear increase with the absolute temperature . The quotient is a material constant and proportional to the coercive force. Natural aging also follows a law of the form , but is not proportional to and therefore does not have a peak value in the zone of coercive force. Natural aging disappears at the remanence and at the coercive force. The constant of natural aging is proportional to the product and inversely proportional to the coercive force. The quotient is, in this case, not a material constant and not proportional to the coercive force.