MAGNETOCRYSTALLINE ANISOTROPY FOR Fe-Al-Si (SENDUST) SINGLE CRYSTALS WITH DO//3 ORDERED STRUCTURE.

The magnetocrystalline anisotropy constants, K//1, of the Sendust alloys (7 to approx. 11 wt. %Si, 4 to approx. 7 wt. %Al, bal. Fe) were determined as a function of the temperature between minus 196 degree C and 600 degree C by means of a torque magnetometer. K//1 is negative at minus 196 degree C and the magnitude is fairly large (e. g. m approx. 10**4 erg/cm**3) for most alloys examined. However, with increasing temperature, K//1 crosses zero and changes in sign from negative to positive. The temperature at which K//1 crosses zero, T//K//1 equals 0, differs remarkably and ranges from minus 140 degree C to 200 degree C for each alloy composition. For the central composition of the Sendust alloy (9. 6 wt. %Si, 5. 7 wt. %Al, bal. Fe), T//K//1 equals 0 was found to be room temperature. No sign change of K//1 took place in the 7. 4 wt. %Si, 4. 1 wt. %Al, bal. Fe alloy. T//K//1 equals 0 for the alloys quenched from 1200 degree C is found to be different from that of the alloys annealed at 1200 degree C. The compositions at which K//1 becomes zero are strongly temperature dependent.