Effect of residual stresses and surface roughness on coercive force in amorphous alloys

The residual stresses in Fe40Ni40(Si+B)19Mo1 and Fe40Ni38B18Mo4 amorphous ribbons have been studied and the thermal treatments necessary to remove them have been performed. Based on this study the dependence of coercivity Hc on the applied stress σ in samples in the as-quenched state and after the thermal treatments have been compared. The results show that the compressive residual stresses are related with the minimum in the curves Hc(σ) for the samples in the as-quenched state and when the residual stresses are removed the minimum nearly disappears. Finally, in samples without surface roughness and without residual stresses the increase of Hc when the applied stress increases is explained by a nucleation term.