Influence of Magnetic Field Direction and Temperature on Rearrangement of Martensite Variants in Fe-31.2at.%Pd

Abstract

We have measured temperature dependence of the uniaxial magnetocrystalline anisotropy constant Ku and the shear stress τr eq required for the twinning plane movement of an Fe-31.2Pd alloy in order to explain the field orientation dependence of rearrangement of martensite variants (RMV) of this alloy in the field-cooling process. Under the [001]P field (P represents parent phase), the RMV occurs perfectly at the temperatures where the measurement was performed; in this case, the magnetic shear stress acting across the twinning plane τmag, which is evaluated from Ku, becomes nearly twice as large as τr eq. On the other hand, under the [011]P field, the RMV occurs partially at all the measuring temperatures; in this case the maximum of τmag is nearly the same as τr eq. It is successful to evaluate the following relation quantitatively; τmag> τr eq is satisfied when RMV occurs under magnetic field.