Dependence of magnetic properties of HDDR Nd-Fe-B bonded magnet on intergranular phase

Abstract

Using proposed different anisotropy expressions K 1′(r) and K 1″(r) at the grain boundary, we investigate the effect of intergranular phase (IP) on the average anisotropy 〈K 1〉 of grain boundary and the coercivity H c of HDDR (hydrogenation, disproportionation, desorption and recombination) Nd-Fe-B bonded magnet. The results indicate that when the IP’s thickness d is zero, 〈K 1〉 and H c based on K 1′(r) are equal to the corresponding ones based on K 1″(r). While d takes nonzero values, 〈K 1〉 and H c based on K 1″(r) falls and rises more rapidly, respectively, with increasing d. When d is 1 nm and the structure defect thickness r 0 is close to the thickness of domain wall (∼4 nm), the calculated coercivity is consistent well with the avaiable experimental data.