High performance Nd-Fe-B permanent magnets without critical elements

• Magnetic properties of Ce and Co co-doped Nd-Fe-B based alloys are investigated.
• Substitution of Ce and Co results in the synergistic effect between Co and Ce3.44+.
• Significant Nd can be replaced by Ce by maintaining good magnetic properties.
• Substitution of Ce and Co in Nd2Fe14B increases both TC and the (BH)max.
• Magnetic properties of V, Cr, Mn, and Ni doped Nd-Fe-Co-B alloys investigated.

Scanning electron microscopy, and magnetization measurements reveal that as cast (Nd1−xCex)2Fe14B alloys contain significant amounts of α-Fe that can be dramatically reduced by annealing the alloys at 1000 °C for 3 days. The room temperature intrinsic coercivity, Hci, of (Nd0.8Ce0.2)2.2Fe14B melt spun ribbons was found to be 11 kOe, which is ∼32–∼10% higher in comparison to that of Nd2Fe14B (Hci = 8.3 kOe), and (Nd0.8Ce0.2)2.0Fe14B (Hci = 10 kOe), respectively. The substitution of Co for Fe in (Nd0.8Ce0.2)2Fe14−zCozB significantly increases both TC and the maximum energy product, (BH)max. Our study shows that both Co-containing and Co-free Ce-substituted Nd2Fe14B alloys have excellent magnetic properties at room temperature and above. The experimental results also demonstrate the potential of Nd-Ce-Fe-TM-B based alloys as alternative to expensive Dy-containing high performance rare earth magnets.