Effect of gallium on the crystal structure and magnetic properties of PrFe11 − x Ga x C y compounds

A homogeneity range of the PrFe_{11 ? x} Ga _x C _y phase was determined. As the gallium content increases, the lattice parameters were shown to increase, whereas the Curie temperature decreases; the type of magnetic anisotropy at room temperature is unchanged. In the alloys with x > 3, the transformation of the tetragonal lattice of the compound into an orthorhombic lattice with the axial ratio a/b ≤ 1.006 is observed. This is likely to be caused by the ability of gallium to form covalent bonds. Gallium atoms were found to occupy preferentially 16j ₂ and 4e ₂ sites in the orthorhombic lattice of the FePr_6.5Ga_4.5C compound. The atoms located in the 16j ₂ sites form wavy chains along the [010] direction of the orthorhombic lattice, whereas the iron atoms located in the 16j ₁ sites form analogous chains along the [100] direction. Owing to this fact, one of these directions is likely to become an easy axis. The alloy with x= 4.5 has a low coercive force at room temperature; at 114 K, its coercive force is H _c = 42.4 kA/m.     

Temperature dependence of the velocity of ultrasound and electrical conductivity of an epoxy composite with a carbon filler

Experimental data are given on the behavior of the velocity of ultrasound and electrical conductivity as a function of the temperature in an epoxy composite material filled with carbon fiber.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 43, No. 3, pp. 413–417, September, 1982.     

Economic-mathematical models for designing a wastewater purification system for electroplating plants

The features of designing wastewater purification systems for electroplating plants at the stage of investment justification were considered. Economic-mathematical optimization models, which can serve as the basis for solving investment planning problems for similar systems with the use of integer linear programming, were developed.