Villari Effect


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Related to Villari Effect: Villari Reversal

Villari effect

[və′lär·ē i‚fekt]
(physics)
A change of magnetic induction within a ferromagnetic substance in a magnetic field when the substance is subjected to mechanical stress.

Villari Effect

 

the effect of mechanical deformation (stretching, twisting, and bending) on the magnetization of a ferromagnetic.

Discovered in 1865 by the Italian physicist E. Villari (1836-1904), the effect is the opposite of magnetostriction— change in the size of a ferromagnetic during magnetization. Ferromagnetics (nickel, for example) that shrink during magnetization (have negative magnetostriction) lose some of their magnetic qualities when stretched (negative Villari effect). On the other hand, the stretching of ferromagnetics with positive magnetostriction (for example, a bar of iron-nickel alloy with 65 percent nickel) leads to an increase in their magnetic properties (positive Villari effect). During compression the sign of the Villari effect switches to its opposite. The Villari effect is explained by the fact that the domain structure of a ferromagnetic, which determines its magnetic properties, changes when mechanical force is applied. It is used in creating materials with given magnetic properties.

R. Z. LEVITIN

References in periodicals archive ?
Effect of stress or strain on magnetization is called the Villari effect, inverse magnetostrictive effect, or piezomagnetism.
This "reverse magnetostriction" is called the Villari Effect and is utilized within the electronics head to detect the ultrasonic pulse on the waveguide, which is described next.
The ultrasonic pulse is a strain wave which is accompanied by a change in permeability (the Villari Effect), as compared with the remainder of the waveguide.