On the Magnetostriction of Iron-Aluminium Alloys and a New Alloy "Alfer"

The magnetostriction of iron-aluminium alloys has been measured by the apparatus designed by the present investigators in various longitudinal fields of less than 1200 Oersteds. The positive magnetostriction of iron gradually increases by the addition of aluminium, while the negative one descreases. All the alloys containing more than 5.90% Al have only a positive magnetostriction, and especially in the case of alloys containing more than 8.80% Al the magnetostriction always increases with the magnetizing field or the intensity of magnetization ; showing no maximum. The magnetostriction at a constant field of 1, 100 Oersteds shows a negative value, in the range of lees than 5.3% Al content, while a positive value in the aluminium content above this percentage. In the range of the aluminium content 11.5-13.2% the magnetostriction is very high ; its highest value being 40×10 of 13.14% Al allcy. These alloys may be excellent magnetostriction materials for a supersonic cscillator and have been called "Alfer" by the present investigators