Magnetocrystalline Anisotropy of Fe-Si Alloy Crystals under Hydrostatic Pressure

Magnetization measurements at room temperature were made for various fields applied in 〈100〉, 〈110〉, and 〈111〉 directions of 6 at. % Si in Fe alloy crystals subjected to hydrostatic pressures up to 5100 bar. All the experimental results are found to agree closely with theoretical curves computed for $K_1^{\text{−1}}{\mathrm{(\partial K}}_1\text{/∂p)\hspace{0.17em}=\hspace{0.17em}−60}$ , $K_2^{\text{−1}}{\mathrm{(\partial K}}_2\text{/∂p)\hspace{0.17em}=\hspace{0.17em}0}$ , and ${\sigma }_3^{\text{−1}}{\mathrm{(\partial \sigma }}_3\text{/∂p)\hspace{0.17em}=\hspace{0.17em}−5.5}$ (all in ${10}^{\text{−7}}\hspace{0.17em}{\mathrm{bar}}^{\text{−1}}$ ), where the anisotropy constants $K_1$ and $K_2$ are 46 and 7 (in ${10}^3\hspace{0.17em}\mathrm{erg}/\mathrm{g}$ ), respectively, and the saturation moment ${\sigma }_3$ , is 204 emu. These values for the pressure dependences of $K_1$ and ${\sigma }_3$ , when converted to volume dependences and combined with thermal dilatation data, can account for some but only a small part of the discrepancy between recent measurements on this alloy and the theoretical l0th-power relation between the variations of $K_1$ and ${\sigma }_3$ with temperature. A similar situation is shown to obtain for pure iron.