The structure and electrical resistance of the alloy Ni45Mn46In9 were studied. At room temperature, Ni45Mn46In9 is ordered into the cubic structure L21, characteristic of Heusler alloys. Throughout the entire temperature range from 77 to 1100 K, a large specific resistance and negative temperature coefficient of resistance are observed. Conductivity obeys Mott’s law T–1/4 with the addition of a metal contribution. The specific features observed in the temperature dependence of the electrical resistance curve suggest that in this alloy the phase transition between the cubic austenitic phase and martensitic phase with lower symmetry, characteristic of ferromagnetic nonstoichiometric Heusler alloys, occurs at an unusually high temperature.

The structure and electrical resistance of the alloy Ni 45 Mn 46 In 9 were studied. At room temperature, Ni 45 Mn 46 In 9 is ordered into the cubic structure L2 1 , characteristic of Heusler alloys. Throughout the entire temperature range from 77 to 1100 K, a large specific resistance and negative temperature coefficient of resistance are observed. Conductivity obeys Mott’s law T –1/4 with the addition of a metal contribution. The specific features observed in the temperature dependence of the electrical resistance curve suggest that in this alloy the phase transition between the cubic austenitic phase and martensitic phase with lower symmetry, characteristic of ferromagnetic nonstoichiometric Heusler alloys, occurs at an unusually high temperature.

Исследованы структура и электросопротивление сплава Ni 45 Mn 46 In 9 . При комнатной температуре сплав Ni 45 Mn 46 In 9 упорядочен в кубическую структуру L2 1 , характерную для сплавов Гейслера. Во всей области температур от 77 до 1100 К наблюдаются большая величина удельного электросопротивления и отрицательный температурный коэффициент сопротивления. Проводимость подчиняется закону Мотта Т –1/4 с добавкой металлического вклада. Особенности, наблюдаемые на кривой температурной зависимости электросопротивления, позволяют предположить, что в данном сплаве характерный для ферромагнитных нестехиометрических сплавов Гейслера фазовый переход между кубической аустенитной фазой и мартенситной с более низкой симметрией происходит при необычно высокой температуре.

The electrical resistance and structure of Ni42+xMn47-xSn11 alloys have been studied; where x=0, 1, 2, 3, 4, At room temperature, Ni42+xMn47-xSn11 alloys are ordered in the cubic L21 Ni2MnSn structure characteristic of Heusler alloys. The phase transition between the cubic austenite phase and martensite with lower symmetry, characteristic of ferromagnetic non-stoichiometric Heusler alloys, is observed at temperatures below room temperature. It was found that the partial replacement of Mn atoms by Ni atoms leads to an increase in the phase transition temperatures and to their shift to room temperature. Keywords: Heusler alloys, electrical resistance, phase transition.

Исследованы электросопротивление и структура сплавов Ni42+xMn47-xSn11, где x=0, 1, 2, 3, 4. При комнатной температуре сплавы Ni42+xMn47-xSn11 упорядочены в кубическую структуру L21 Ni2MnSn, характерную для сплавов Гейслера. Характерный для ферромагнитных нестехиометрических сплавов Гейслера фазовый переход между кубической аустенитной фазой и мартенситом с более низкой симметрией наблюдается при температурах ниже комнатной. Обнаружено, что частичная замена атомов Mn атомами Ni приводит к повышению температур фазового перехода и к смещению их в область комнатных температур. Ключевые слова: сплавы Гейслера, электросопротивление, фазовый переход.

The concentration dependence of the resistance of the alloys of Ni3MnxAl1−x system is described in the framework of the percolation theory in the model of an effective medium. The regions corresponding to the alloys of terminal compositions are present in the entire volume of the samples. The formation of an infinite cluster occurs near the percolation threshold x=0.3 for the phase of the Ni3Al and x=0.7 for the phase of the Ni3Mn type. This makes it possible to suppose that in the ternary Ni3MnxAl1−x alloys in the intermediate region of concentrations there is realized an inhomogeneous heterophase structure.

Kinetic properties of Ni 3 Mn x Al 1 − x alloys have been studied at temperatures of 4.2 to 800 K in magnetic fields up to 12 MA/m. Separate contributions to the electrical resistance have been determined: the residual resistance, phonon component, and magnetic component. The behavior of the kinetic properties typical of the ferromagnets is observed, including the positive temperature coefficient of resistance and features in the form of a bend in the curves of the temperature dependence of resistance at the Curie temperature. It is shown that the parameters of the investigated kinetic properties change substantially upon the isomorphic concentration transition L 1 2 → L 1 2 from the ordinary superstructure of Ni 3 Mn type to the Ni 3 Al intermetallic compound. It has been revealed that the concentration dependence of the resistance can be described in terms of the percolation theory in the model of effective medium.

Magnetic properties of Ni3Al1-yMny alloys at y≤0.6 were investigated at T≤400 K in magnetic fields H≤4 MA/m. The concentration y dependencies of the spontaneous magnetic moment s, the effective magnetic moment eff, the Curie temperature ТС, the Weiss constant , and the temperature independent part of the magnetic susceptibility 0 were determined. The behavior of the Rhodes-Wohlfarth parameter р(y) in the transition region from the itinerant electron magnetism to the spin localized one is related to the increase in the spontaneous magnetic moment of Ni atoms inversely proportional to the average distance between Mn atoms with the highly localized magnetic moments.

Effect of the composition of liquid monomer-solvent mixtures on the processes of impregnation and subsequent reinforcement of solid chalkstone samples by the monomer polymerization in pores was considered. Factors influencing the rate of the solution-monomer mixture penetration in pores of a solid were studied.

The interaction of cellulose macromolecules of fabric fibers with a (meth)acrylic (co)polymer was studied by microcalorimetry and IR spectroscopy.

Paramagnetic susceptibility of alloys Ni3Al x Mn1 − x in the field of the transition between the ferromagnets described in the band theory (Ni3Al) and in the spin-localized (Ni3Mn) model of magnetic moments has been investigated. The concentration dependences of the paramagnetic Curie temperature, effective magnetic moment, and temperature-independent component of magnetic susceptibility have been determined.

Thermal oxidative degradation of composites consisting of two incompatible polymers was studied by gravimetry and gas chromatography-mass spectrometry.

The Mössbauer spectra of PdMnxFe1-x alloys obtained at 80 K and at 300 K were studied in the 0.2 < x < 0.8 concentration range, in which there realizes a microinhomogeneous multiphase medium formed by isostructure phases of the constituent compositions: ferromagnetic PdFe (ТС=730 К) alloy undergoing atomic ordering and antiferromagnetic PdMn (TN=815 К) intermetallic compound. Magnetic properties studies evidence the presence of a third presumably noncollinear phase with its own ordering temperature lying below the Curie temperature of the ferromagnetic phase in the 0.2 < x < 0.8 concentration range. The Mössbauer spectra at 300 K exhibit a doublet for antiferromagnetic alloys (x > 0.8) and a sextet at Hhf ~350 kOe for ferromagnetic alloys (x < 0.2). In the intermediate concentration range several peaks 0 < Hhf < 350 kOe have been observed in the P(Hhf) curves, which result from microinhomogeneous multiphase state.