TY - JOUR
AU - Ramamoorthy Ramesh
AB - The effect of post sintering heat treatments on the intrinsic coercivity of Fe-Nd-B magnets is studied. It is shown that the large anisotropy in thermal expansion coefficients in the a and c directions of the tetragonal unit cell as well as the anisotropy in thermal expansion properties between the matrix and the grain boundary phase, will lead to stresses upon quenching from the sintering temperature. The effect of stresses due to water quenching have been incorporated into the model developed in the companion paper (Part I). This quenching stress manifests itself as a stress anisotropy constant, which opposes the magnetocrystalline anisotropy constant. Thus, the effective anisotropy field, near the interfaces, is reduced from its value in an optimally cooled sample, leading to a lower iHc. It is also shown through step quenching experiments that the effect of quenching stresses can be nullified by cooling slowly to below a specific temperature following which quenching does not influence the intrinsic coercivity.
BT - Journal of Applied Physics
DO - 10.1063/1.346946
LA - eng
M1 - 11
N1 - cited By 12
N2 - The effect of post sintering heat treatments on the intrinsic coercivity of Fe-Nd-B magnets is studied. It is shown that the large anisotropy in thermal expansion coefficients in the a and c directions of the tetragonal unit cell as well as the anisotropy in thermal expansion properties between the matrix and the grain boundary phase, will lead to stresses upon quenching from the sintering temperature. The effect of stresses due to water quenching have been incorporated into the model developed in the companion paper (Part I). This quenching stress manifests itself as a stress anisotropy constant, which opposes the magnetocrystalline anisotropy constant. Thus, the effective anisotropy field, near the interfaces, is reduced from its value in an optimally cooled sample, leading to a lower iHc. It is also shown through step quenching experiments that the effect of quenching stresses can be nullified by cooling slowly to below a specific temperature following which quenching does not influence the intrinsic coercivity.
PY - 1990
SP - 5772
EP - 5777
T2 - Journal of Applied Physics
TI - A microstructure based magnetization reversal model in sintered Fe-Nd-B magnets. II. Effect of post sintering treatments
VL - 68
SN - 00218979
ER -