Abstract
Magnetostrictions in Alnico 5 magnet were measured by means of a strain gauge. Magnetostriction remarkably depends on the direction of heat-treatment in magnetic field—tendency similar to that in other metals. Then by aging at 600°C, magnetostriction decreases on the whole at a direction perpendicular to the field of heat-treatment in magnetic field and in heat-treatment without magnetic field, and conversely, increases at a direction parallel to the field treatment. This is an interesting phenomenon for discussion of the structure of such materials. A faster cooling after fusion causes an increase in magnetostriction. The starting ponit of magnetostriction curve shifts to the side of lower magnetizing force, which is a property in soft magnetic material. In this state, powder patterns can be observed. A heating at 900°C, or a temperature between 1000° and 1200°C at which γ phase is produced, causes a magnetostriction curve distinctly different from that after heating at 950° or 1300°C which are solution temperatures.
