Measurement of magnetostriction within the temperature range - 196 to 400  C

An apparatus is described which permits the magnetostrictive behaviour of small single-crystal or polycrystalline specimens to be investigated over a range of temperatures from - 196 to 400° C. Resistance strain gauges are employed and the performance of a number of gauges has been investigated at these temperatures. Details are given of the techniques used to obtain a reliable overall strain sensitivity of 2 × 10 -7 per mm deflexion of the indicating galvanometer. The procedure by which the single-crystal magnetostriction constants may be obtained from strain measurements at saturation is outlined for the case of a disk-shaped crystal in which the plane of the disk is normal to one of the three principal crystallographic directions.