Improvement of the magnetic properties of low-neodymium magnets by minor addition of titanium

Rapidly solidified nanocomposite Nd₉Fe_77−xB₁₄Ti_x alloys, consisting of magnetic Nd₂Fe₁₄B phase and soft magnetic phases, were investigated. The effect of titanium addition on the structure and magnetic properties was studied. It was found that 2–4 at% Ti addition leads to substantial increase of the coercivity and maximum energy product, maintaining the remanence unchanged. The highest properties: J_r=0.81 T, _JH_c=907 kA/m, (BH)_max=99 kJ/m³, were achieved for the Nd₉Fe₇₃B₁₄Ti₄ alloy. This effect we attribute to the formation of fine and homogeneous grain structure and a change of the phase morphology in the Ti-containing alloys. The initial magnetization curve indicates a change of the coercivity mechanisms giving rise to pinning of domain walls, which is caused by reduction of the crystallite size.