Improvement of thermal stability in hot-deformed Nd-Fe-B magnets by grain refinement

Achieving ultrastrong anisotropy in bulk Pr2Fe14B/α-Fe nanocomposite magnets by high-pressure thermal compression

“…And the low coercivity ( H ci < 5 kOe) has become a crucial drawback to further improving the magnetic properties of the (Nd/Pr) 2 Fe 14 B/α-Fe bulk nanocomposite magnets [16,18,19,27]. Hence, the coercivity enhancement, which can be obtained by microstructure manipulation (e.g., grain refinement [30], microalloying [31], interfacial modification [32,33] and ordered gradient structures [9,34], etc. ), will be the major issue in our future work and the related study is in progress.…”

Accelerated discovery of cost-effective Nd–Fe–B magnets through adaptive learning

“…Ni could potentially benet Nd-Fe-B in two aspects: (1) Ni possesses a higher T C than Fe, and hence benets ß H cj as well as a B r , resulting in the improved HT performance of Nd-Fe-B, similar to that of Co; (2) Ni is found to be able to effectively reduce the grain size of the Nd-Fe-B microstructure, leading to higher H cj and ß H cj . 79 For example, ß H cj of 3: C2 (La 1 -Ce 1 Ni 0.25 ) at 150 °C is −0.590% per °C, which is superior to the value of −0.600% per °C for pristine Nd-Fe-B (ESI † Fig. S7).…”

Significant Progress for Hot-Deformed Nd-Fe-B Magnets: A Review

“…were also attempted to enhance the coercivity using the DADP. However, the doping of Nd-M alloy powders, such as Nd-Cu, Nd-Cu-Al and Nd-Fe-Ga-Cu, showed unremarkable results in the increase in coercivity (<2.1 T) [ 24 , 65 , 69 , 70 ]. Notably, the doping of Pr-M alloy powders, such as Pr 70 Cu 30 and Pr 90 Ga 10 , obtained considerable coercivity levels above 2.3 T [ 71 , 72 ].…”

“… Temperature coefficient of coercivity (25–180 °C) vs. grain size for various types of HRE-free Nd-Fe-B magnets. Reproduced with permission [ 24 ]. Copyright 2020, Elsevier.…”

“…The thermal stability of coercivity is evaluated by the temperature coefficient of coercivity ( β ), which is defined by the following equation: where T is the working temperature of magnets. The relationship between the temperature coefficient of coercivity (25–180 °C) and grain size for various types of Nd-Fe-B magnets (HRE-free) is illustrated in Figure 3 [ 24 ]. Similar to the relationship between coercivity and grain size, the temperature coefficient of coercivity also exhibits a logarithmic correlation with grain size.…”