Magnetostriction – what is it, how to check?

Although the phenomenon of magnetostriction has been known for many years, it still fascinates scientists, who have only recently begun to find practical applications for it. The first observations were made by British physicist James Joule in 1842. While observing the magnetization of steel and iron, he noticed that under the influence of a magnetic field, the materials under investigation underwent deformation. Almost two centuries have passed since then, and yet this phenomenon has not been fully explored, and new applications are still being found for it. The inverse effect is called the Villari effect – in this case, changes in external dimensions affect changes in magnetic properties. For many years, magnetostriction had no practical application. This was because traditional materials such as cobalt, nickel, or iron deformed to a very small extent. A magnetostriction coefficient of 0.05% was too low to be practically utilized, as there were no such strong magnetic fields. Modern materials, developed in the second half of the 20th century, have greatly changed the possibilities of using magnetostriction, allowing for a coefficient of about 0.2%. They are based on rare earth elements such as dysprosium and terbium, in various percentage compositions. Currently, the most commonly used alloy contains 67.5% Fe, 9.6% Tb, and 22.9% Dy.