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Annealing of a (Pr0.53Dy0.47)12(Fe0.77Co0.23)80B8 (at %) alloy is found to affect the magnetic properties of the sintered magnets fabricated from the alloy. Annealing of the alloy is shown to lead to a 8% increase in the remanence and to nonmonotonic variations of the coercive force by 10–12%. The detected 4% decrease in the dysprosium content in the main magnetic phase and 1% increase in the phase content in the sintered magnet can favor an increase in the residual magnetization. Annealing of the alloy does not lead to changes in the temperature coefficient of induction of the sintered magnets. The diffusion of dysprosium is the most probable cause for the detected changes.

The time changes in the magnetization of the magnets (Pr0.51Dy0.49)13(Fe0.64Co0.36)80B7 and (Pr0.51Dy0.49)13(Fe0.64Co0.36)79Cu1B7 (at %) sintered at 160°C are studied. Alloying of the Pr–Dy–Fe–Co–B materials with copper is shown to cause a decrease in the magnetization losses in time.

—Changes in the magnetic properties of the sintered (Pr0.76Dy0.24)12.9(Fe0.53Co0.47)81.5B5.6 material, which are caused by solid-phase alloying with the (Pr0.63Dy0.37)(Fe0.31Co0.69)2B2 alloy are studied. The dependences of the phase composition and the coercive force of the sintered material on the amount of the added alloy is obtained. As the boron content in the sintered material increases, the content of the main magnetic (Pr, Dy)2(Fe, Co)14B phase decreases from 89.2 to 51.4 vol % and the content of the (Pr, Dy)(Fe, Co)3 phase increases from 7.1 to 43.9 vol %. It was found that, in the course of 190-h storage of sintered magnets in air, their coercive force and density are first unchanged and subsequently decrease; the coercive force decreases to zero.

The effect of cobalt on the oxidation resistance of (Nd0.85Dy0.15)16.4(Fe0.89Co0.11)74.4Ti1.3B7.9 and (Pr0.56Dy0.39Sm0.05)14.5(Fe0.75Co0.25)78.8B6.7 alloys has been studied. The storage of magnet blanks made from these alloy in air for 200 h does not affect the magnetic properties of the sintered magnets owing to the presence of the phases (Pr, Dy)(Fe, Co)2, (Pr, Dy)(Fe, Co)2B2, (Pr, Dy)(Fe, Co)4B, (Pr, Dy)(Fe, Co)3B2, and (Pr, Dy)(Fe, Co)3, which are resistant to oxidation and ensure liquid-phase sintering of magnets. After 200-h exposure to air, oxidation of the blanks takes place, the rate of which decreases by more than two times at the expense of an increase in the cobalt content in the alloy.

The properties of sintered magnets (Pr1 − xDyx)-(Fe1 − yCoy)-B (x ≳ 0.6 at %, y ≳ 0.2 at %) as functions of the milling time and the sintering conditions are studied. Minima in the coercive force and the density as functions of the sintering temperature are detected. The dependence of the minimum depth on the milling time is detected. In the case of long-term sintering or additional sintering, the values of these parameters are restored. The minimum in the (Pr1 − xDyx)-(Fe1 − yCoy)-B (x ≳ 0.6 at %, y ≳ 0.2 at %) materials is assumed to be related to the deceleration of diffusion processes in them as compared to the (Nd1 − xDyx)-(Fe1 − yCoy)-B (x = 0.71 at %, y = 0.34 at %) system, in which this minimum is insignificant.

The effect of 3 wt % additions, the compositions of which are close to those of intermetallic compounds, on the properties of the magnets prepared from a base Nd15(Fe0.98Co0.02)balTi1.4Cu0.6B7.5 alloy has been studied. It is shown that the effect of additions on the coercive force of the magnets increases as the dysprosium content increases.

Sintered (Nd1 − x − z Dy x Sm2)-(Fe1 − y Co y )-B (atomic fractions x = 0.27, 0.32, 0.39; y = 0.17, 0.23, 0.28; and z = 0.04–0.18) materials have been studied. It is shown that the magnetic moments of samarium ions and the iron-cobalt sublattice are ordered antiferromagnetically and, as the samarium content increases, the content of dysprosium and samarium in the basic A magnetic phase decreases and increases, respectively. As the samarium content (z) in sintered magnets (Nd0.61 − z Dy0.39Sm z )17.5(Fe0.72Co0.28)76.3B6.2 increases, the thermal induction coefficient is found to decrease monotonically from 0.021 to 0.006%/°C, i.e., by 3.5 times. In this case, residual inductance B r is unchanged (0.8 T).