Permanent magnets based on R-Fe-B and R-Fe-C alloys

Abstract

A review is given on the basic properties of 2:14:1 hard magnetic phases as well as technological procedures used for manufacturing R-Fe-B and R-Fe-C permanent magnets. First, we analyse the phase diagrams, crystal structure of hard magnetic phases and composition ranges in which these phases form solid solutions, as a result of various types of substitution. Then, the magnetic properties of R 2 Fe 14 B-, R 2 Fe 14 C-and R 2 Co 14 Bbased compounds are described. The routes used for manufacturing R-Fe-B and R-Fe-C permanent magnets are detailed. The magnets' microstructure as well as their coercivities are described in correlation with composition and manufacturing routes. The properties of nanostructure magnets are then presented. Finally, the stability of Nd-Fe-B and Nd-Fe-C magnets in various working conditions is analysed.

Spin reorientation process in Tm2–xHoxFe14B – analysis of conical arrangement based on Mössbauer spectra

“…The program is based on crystal fi eld and exchange parameters, quantum numbers, Curie temperatures, and the anisotropy constant. The entry parameters (see Table 1) were taken from the literature [12,13] as well as calculated using our earlier work [14]. The utilized procedure allows us to determine the position angle of vector M  by minimizing the free energy function F(T) of two coupled sublattices -associated with R atoms and Fe atoms.…”

Задержанные скачки размагничивания в магнитах (NdDy)(FeCo)B в стационарном магнитном поле

“…С другой стороны, энергия E, необходимая для перемагничивания объема V образца в приложенном магнитном поле H = 9 kOe составляет E = 2 M · H = 0.002 emu · 9000 Oe = 18 erg. Как известно, ширина доменных стенок в магнитах семейства RE−T M−B составляет 50−80 nm, что значительно больше, чем период решетки 12 ¦ в направлении легкой оси на-магничивания [2,3]. Поэтому механизмы торможения доменных стенок, связанные с влиянием периодического потенциального рельефа Пайерлса на их подвижность полностью исключаются.…”

“…На сегодняшний день такие магниты представляют собой усовершенствование исходной версии NdFeB [3] и по многим характеристикам (энергетическое произведение, остаточная намагниченность, временная стабильность и др.) остаются непревзойденными.…”

Influence of Carbon on Spin Reorientation Processes in Er2-xRxFe14C (R = Gd, Pr) - Mössbauer and Magnetometric Studies

“…Since the discovery of unique magnetic properties of Nd 2 Fe 14 B permanent magnets, a great number of studies were devoted to R 2 Fe 14 B compounds, where R is a rareearth [1][2][3][4][5][6][7]. Less attention was put on carbides R 2 Fe 14 C, which are known to be less stable than borides.…”

“…It was studied previously for different rare earth ions [1][2] in borides and for few carbide compounds R=Nd, Er, Gd. Also, change of magnetic structure with increasing temperature (axis/plane) takes place in Er 2−x Fe 14+2x Si 3 compound [10] with P 6 3 /mmc structure type.…”