[en] Sintered Nd-Fe-B permanent magnets show a step in the second-quadrant demagnetization curve. Demagnetization curves of sintered Nd₁₅Fe₇₇B₈ samples measured at different temperatures are given and discussed in the frame of magnetic grain orientation. The most important demagnetization process is reversed-domain nucleation. In order to estimate the measured dip in magnetization curves theoretically three phases are considered: the non-magnetic phase, hard magnetic grains with given nucleation field, and soft magnetic grains