Role of boron in the formation of the magnetic properties of sintered Nd-Dy-Fe-Co-B materials with a high cobalt content

Sintered materials having the compositions (Nd_{1 ? x} Dy _x ) _S (Fe_{1 ? y} Co _y )_balB_6–8 (atomic fractions x = 0.09–0.71, y = 0.19–0.34, S = 13.3–15 at %) have been studied. It is shown that, as the content of the boron-containing (Nd, Dy)(Fe, Co)₄B phase increases, the coercive force decreases abruptly. This effect is explained by the transition of boron atoms from the principal magnetic boron-containing (Nd, Dy)₂(Fe, Co)₁₄B phase to the (Nd, Dy)(Fe, Co)₄B phase during sintering.     

Effect of copper on the properties of Pr-Dy-Fe-Co-B sintered magnets

The effect of copper on the properties of magnets (Pr_0.52Dy_0.48)₁₃(Fe₆₅Co_0.35)_{80.3 ? x} Cu _x B_6.7 (x = 0–10) has been studied. Alloying with copper is shown to decrease the sintering temperature and to increase the content of the principal (Pr,Dy)₂(Fe,Co)₁₄B magnetic phase. For compositions with x = 1.3–3.3, copper is found to affect the value and sign of the temperature induction coefficient (TIC). It is shown that the effect of copper on the TIC is determined by the substitution of copper ions for iron ions in lattice sites, which are coupled via an antiferromagnetic exchange interaction.     

Sintering of Pr-Dy-Fe-Co-B materials

The properties of sintered magnets (Pr_{1 ? x} Dy _x )-(Fe_{1 ? y} Co _y )-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 (Pr_{1 ? x} Dy _x )-(Fe_{1 ? y} Co _y )-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 (Nd_{1 ? x} Dy _x )-(Fe_{1 ? y} Co _y )-B (x = 0.71 at %, y = 0.34 at %) system, in which this minimum is insignificant.     

Mechanical properties of sintered materials

Published as a discussion in continuation with the series of papers [1, 2] on mechanical properties.     

The mechanical properties of sintered materials. I. The strength properties of sintered materials

Translated from Poroshkovaya Metallurgiya, No. 1(337), pp. 34–45, January, 1991.     

Mechanical properties of sintered materials. III. Cold brittleness of sintered materials

Translated from Poroshkovaya Metallurgiya, No. 5(341), pp. 38–49, May, 1991.     

Effect of heat treatment on the properties of nanostructured magnetically hard Pr-Dy-Fe-Co-B materials

Effect of heat treatment (HT) in the temperature range from 400 to 1000°C on the properties of sintered (Pr_{1 − x} Dy _x )_{12 − 17}(Fe_{1 − y} Co _y )_balB_{5 − 15} (x = 0−0.73 and y = 0.15−0.87) magnets is studied. It is shown that, depending on the cobalt and boron contents in the material, its composition and the dependence of H _cI on heat treatment conditions change. In the HT temperature range 700–900°C, an H _cI minimum is found: the “depth” of the minimum increases with increasing cobalt content. The minimum of H _cI is reversible; i.e., after HT at 1000°C, the coercive force increases to the value corresponding to the composition of the material whatever the temperature of preliminary HT. A model that explains the dependence of H _cI of the material on the HT conditions by a diffusion redistribution of boron between the basic R ₂F₁₄B (2-14-1 intermetallic) and RF ₂, RF ₄B, RF ₃B₂, and RF ₂B₂ phases (with R = Pr + Dy, F = Fe + Co) is suggested.     

铜含量对铝铜烧结材料性能影响

用粉末冶金法制备了Al-Cu合金块体烧结材料,研究了不同铜含量对烧结温度、微观形貌和抗压强度性能的影响。研究表明,对于不同铜含量的样品,存在不同的局部熔化区间。在局部熔化区间内对应一优化烧结温度。在此温度下烧结时样品仅发生局部熔化,烧结后制品外观和尺寸不会发生大的改变。烧结制品抗压强度随着铜含量的增加先上升后下降。温度为555℃时,7.5%铜含量的抗压强度达到最大值。铜元素的加入改变了烧结体内部组织和孔隙数量大小。     

用粉末注射成形(PIM)制造高性能烧结材料

这篇论文主要研究了用粉末注射成形工艺制造各种高性能与功能烧结材料时，需要的显微组织控制。     

Control over the properties of sintered ductile materials

Conclusions Maximum elongations at a given density have been established for materials of various types of porosity. The elongation of materials of isolated porosity is more than twice that of materials of open porosity. A simple quantitative relationship has been found between elongation and the characteristic =. Simple experimental methods have been developed for determining this characteristic with satisfactory accuracy. Invariant relationships have been found between elongation and ultimate tensile strength. Knowledge of these quantitative relationships is essential in development work on processes enabling the properties of sintered ductile materials to be regulated and on methods of exercising control over these processes.Translated from Poroshkovaya Metallurgiya, No. 9(201), pp. 36–44, September, 1979.     

Electrophysical properties of gadolinium tellurite-boron oxide sintered materials

Translated from Poroshkovaya Metallurgiya, No. 11, pp. 68–71, November, 1990.     

Structure and properties of sintered iron-graphite materials alloyed with nickel and phosphorus

Summary A study was made of the influence of alloying with nickel and phosphorus on the structure and properties of sintered iron-graphite materials. The structural study was carried out by x-ray and electron diffraction methods, and in addition the wear resistance and strength characteristics of the materials were determined.Translated from Poroshkovaya Metallurgiya, No. 3 (51), pp. 52–55, March, 1967.     

模具润滑温压成形法制作的高密度铁基烧结体的磁性与组织

烧结铁是一种好的软磁材料,但其磁通密度比铸造材料的低。低的磁通密度是由于密度低所引起的。本研究开发了一种温压与硬脂酸锂模壁润滑技术(WC-DWL)。使用该技术,得到了密度非常高的成形体。纯铁粉在1176MPa的压力下成形,经1523K烧结后的性能如下:密度=7.76Mg/m3,μm=5300,B160=1.16T,B240=1.28T,B400=1.40T,B2k=1.60T,bHc=110A/m。一些烧结铁表现出各向异性的变化与组织,这导致异常晶粒长大到长度为数毫米。这种异常长大在试样成形密度较高时更为明显。