Martensitic transformations in Ti (Ni,Fe) alloys

In this work we used x-ray structural analysis to investigate the martensitic transformations (MTs)B2R andRB19 in Ti(Ni, Fe) alloys containing 1, 2.5, 4, 5 at. % Fe, and the effect of heat treatment on the MT temperatures and sequence. In the majority of cases, it was found that the MTB2R proceeds through a two-phase region (+R). Heat treatment leads to a narrowing of the temperature interval of the existence of the two-phase region, weakly affects the onset temperatures of the MTsB2R T_R andRB19 M_s, and sharply increases the temperature-of the end of the MT M_e. The existence of the two-phase region is related to the two MT channelsB2R andB2B19 initially intrinsic to the allovs of the given compositions.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 19–22, December, 1989.     

Anharmonicity correction and potential constants: BH 4 − isotopic ions

Normal coordinate analysis for XY₄ type molecules of T symmetry has been carried out by the Wilson F — G matrix method. Following Dennison and making use of the spectral data the anharmonicity factors for B'H ₄ ^– , B'D ₄ ^– , B¹⁰H ₄ ^– and B¹⁰D ₄ ^– have been calculated and potential constants have been evaluated for borohydride isotopic ions.     

A solution spectrum of the nonlinear Schrödinger equation. II

It was shown in a previous communication that the nonlinear Schrödinger equation exhibits a spectrum of eigenfunctions of the form = _k,A _k (coshkx) ^–k and = _k B _k (coshkx) ^–k–1sinhkx, and the corresponding eigenvalues of the energy are related to a band structure with a characteristic energy gap as a significant feature. In the present paper, it is shown that a further spectrum exists exhibiting the general structure = _k=0 A _k(cosh kx)^–k–1/2and = _k=0 B_k(cosh kx)^–k–3/2sinhkx and yielding also a band structure. An extension of the solution spectrum to a nonlinear Klein-Gordon equation and a nonlinear Dirac equation does not imply essential difficulties, and the corresponding characteristic band structure has to be related to a mass spectrum.     

Electrodynamics Under a Possible Alternative to the Lorentz Transformation

A generalization of the classical electrodynamics for systems in absolute motion in presented using a possible alternative to the Lorentz transformation. The main hypothesis assumed in this work are: a) The inertial transformations relate two inertial frames: the privileged frame S and the moving frame S with velocity v with respect to S. b) The transformation of the fields from S to the moving frame S is given by H = a(H – v × D) and E = a(E + v × B), where a is a matrix whose elements depend of the absolute velocity of the system. c) The constitutive relations in the moving frame S are given by D = E, B = H and J = E. It is found that Maxwell's equations, which are transformed to the moving frame, take a new form depending on the absolute velocity of the system. Moreover, differing from classical electrodynamics, it is proven that the electrodynamics proposed explains satisfactorily the Wilson effect.     

The axiomatic foundations of the theory of special relativity

In this paper it is shown that (1) linear transformations more general than the Lorentz transformation—containing the Palacios and the Lorentz transformation as special cases—(2) and the principle of the constancy of the velocity of light (taken originally by Einstein together with the supposition of the linearity of transformation as fundamental hypotheses of the theory of special relativity)—can be deduced from Maxwell's equations for the electromagnetic fieldin vacuo (A ₁), the principle of relativity (A ₂) and the two following axioms (which do not contain explicitly the hypothesis of the isotropy of space!): (A ₃) to every event in the Galilean reference systemS there corresponds one and only one event in the systemS so that these two systems are connected by reversible single-valued functions, continuously differentiable as their inverse transformations, (A ₄) the constant relative velocitiesv _ss andv _ss betweenS andS are each other equal in magnitude and opposite in signv _ss =–v _ss To obtain uniquely the Lorentz transformation the following axiom has to be added: (A ₅) the distanceD of any two points at rest inS, situated in a plane orthogonal to the relative velocity betweenS andS is measuredS as independent of the sense of the velocity, i.e. if one changesv _ss into –v _ss the distanceD does not vary for an observer inS. Results of our theory are the ideas that (a) the fact that the Lorentz transformation is not the unique transformation leaving Maxwell's equations for the electromagnetic field in all Galilean systems of reference invariant but that there exists a more general transformation (containing these two transformations as special cases) leaving Maxwell's equations invariant; (b) that the Michelson-Morley as well as the Fizeau experiment does not represent an experimental proof in favour of the theory of special relativity. At the end of the paper the mutual relations between the principle of relativity (the axiomA ₁ together with the axiomA ₂), the axiomA ₅ and the possibility of the discernibility as well as the indiscernibility of right and left at the macrocosmic level is discussed.     

Continued fractions and fermionic representations for characters of M(p,p′) minimal models

We present fermionic sum representations of the characters _{, s} ^{(p, p)} of the minimal M(p,p) models for all relatively prime integers p>p for some allowed values of r and s. Our starting point is biomial (q-binomial) identities derived from a truncation of the state counting equations of the XXZ spin 1/2 chain of anisotropy –=–cos((p/p)). We use the Takahashi-Suzuki method to express the allowed values of r (and s) in terms of the continued fraction decomposition of {p/p} (and p/p), where {x} stands for the fractional part of x. These values are, in fact, the dimensions of the Hermitian irreducible representations of SU _q- (2) (and SU _q+ (2)) with q–=exp(i{p/p}) (and q+=exp(i(p/p))). We also establish the duality relation M(p,p) M(p–p,p) and discuss the action of the Andrews-Bailey transformation in the space of minimal models. Many new identities of the Rogers-Ramanujan type are presented.Dedicated to Prof. Vladimir Rittenberg on his 60th birthday     

Phase transformations in Cu-Sn alloys containing Ni,Al, Ge,and In

After quenching from 700C and aging, Cu-Sn alloys containing Ni and Al were found to have a precipitation of-solid solution, with a DO₃ type of ordering, of metastable ,, and phases. It was established that the phase has an 4 type of ordering while the phase has the Cu₃Ti type. Observations revealed that Cu-Sn-Al alloys contained two phases, and, with an identical structure but with different ratios of electron concentration per atom.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 34–37, April, 1981.     

A Pulsed-Periodic, Low-Pressure Volume Discharge in Chlorine and in a Xenon/Chlorine Mixture

The electrical and optical characteristics of a self-initiated, low-pressure, pulsed-periodic discharge in chlorine and in a xenon/chlorine mixture are investigated. A volume discharge not bounded by dielectric walls was triggered in a spherical anode–plane cathode system of electrodes on supply of a constant positive-polarity voltage to the anode. The discharge existed in the form of a unit domain. The spatial, spectral (in the range 150–350 nm), and time characteristics (voltage, current, and photocurrent of total radiation of plasma in the spectral range 200–700 nm) of the volume discharge are investigated. Optimization of the pressure and of the structure of the working medium is carried out to obtain the maximum brightness of UV–VUV radiation of the bands of the Cl₂(D–A), Cl₂ ^**, and XeCl(D, B–X) molecules. The results obtained are of interest for being used in a pulsed-periodic, excimer-halogen low-pressure lamp.     

Dynamic recovery,strain hardening and flow stress in hot working of 316 steel

The strain hardening rate was determined as a function of flow stress in torsion tests over the range 900–1200 °C, 0·1–5·0s^–1 in both as-cast and worked 316 stainless steel. Changes in slope of the- curves and extrapolation to the=0 axis permitted determination of the saturation stress _s ^* , and the critical strain for recrystallization which could be compared with the peak in the flow curve. Analysis of the dependence on temperature and strain rate showed that the data could be fitted either to the Kocks-Mecking equations or to the sinh and Arrhenius functions. The flow stresses and the empirical constants in the above equations are compared with those of 304 and 317 steels which contain less and more Mo, respectively.Presented at the 4th International Symposium on Plasticity of Metals and Alloys, Srní, Czechoslovakia, September 7–11, 1987.     

Sensitivity of approximate formulas for determining optical constants of thin films

The sensitivity of approximate formulas for determining the optical constants of thin films using measurement of reflectancesR and transmittancesT at normal incidence have been investigated theoretically. The ranges of refractive indexn, absorption indexk,2nk (=₂) andn ²–k ²(=₁) within relative errors of 5%, 10%, and 20% may be obtained. Selected signs of (₁)⁺ or (₁)^– have been determined. Validity of the condition n₀ A=n _s A has been also evaluated (A=1–R –T andA=1–R–T).     

Time evolution of infinite classical systems with singular,long range,two body interactions

Existence of dynamics for infinitely many hard-spheres inv dimensions is proven in a set of full equilibrium measure.Singular unbounded perturbations are considered with pair potentials diverging as (x – a)^–, >2 anda is the hard-core diameter. Long range forces are allowed with potentials decreasing at infinity asx , <v. The result corrects and generalizes a proof given in a previous paper by the same authors.Research partially supported by a CNR fellowship Posit. 204530.Research partially supported by a CNR fellowship.     

In situ X-ray investigation of deformation martensite in titanium nickelide

X-ray structural analysis was used to carry out an investigation of the martensitic transformation in titanium nickelide during mechanical loading. A diffractometer with filtered cobalt radiation was used, along with an attachment that allowed the sample to be loaded by bending. No R-martensite was observed during loading. The structure of deformation martensite was identified as monoclinic B19. When deformation is increased, the martensite has a more complicated structure and was identified as a mixture of monoclinic B19 and triclinic B19 phases. When the load is removed, the triclinic martensite disappears without hysteresis, whereas a small amount of monoclinic martensite remains and disappears only when heated to 40–60C.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 39–41, May, 1991.     

Nonelastic behavior of Ni50Ti50-xZrx alloys during B2 ⇆ B19′ martensite transformation

The results of an investigation of martensite transformations (MT), the shape memory effect (SME), and their interaction in Ni₅₀Ti_50-xZr_x alloys (1x50 at. %) are presented. The temperature dependencies of electroresistance and the magnitudes of deformation accumulation and recovery in a torsion mode under conditions of a continuously applied external load were investigated. Structural testing of the alloys was carried out by means of x-ray diffractometry methods. It was revealed that during cooling—heating cycling in alloys containing not more than 15 at. % of Zr, B2 B19 MT occurs. In alloys with 30 and 50 (binary NiZr) at. % Ar, under these conditions phase transformations are not observed. With increase in the concentration of the alloying element an increase in the critical temperatures of the MT was observed, the principal shape of the(T) curve changed, and the sequence of the B2 B19 transition was preserved. The SME in Ni₅₀Ti_50-xZr_x alloys was conditioned by the B2 B19 MT, had a single-stage character, and appeared when the Zr content in the alloy did not exceed 15 at. %. The maximum level of accumulation of inelastic deformation _max did not depend on the quantity of the alloying element and was 10–12%.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 37–39, March, 1995.     

The effect of low-temperature electron irradiation on the transition temperature of YBa2Cu3O7−δ superconductors

Measurements of the complex susceptibility =–i of electron-irradiated YBa₂Cu₃O_7– show a strong influence of the electron irradiation dose, ·t on the transition temperatureT _c . For irradiation doses of ·t=2.2·10¹⁹ e^–/cm² we find a damage rate of T _c /(·t)=–1.6·10^–19 K/(e^–/cm²). It is assumed that the decrease ofT _c is mainly a bulk effect due to the production of atomic defects like vacancies and interstitials in the Cu–O–Cu chains and in the basal planes of the unit cells.     

Laser-Induced Flourescence Excitation Spectroscopy and Photophysics of Naphthalene Bichromophoric Molecules in Supersonic Jets

We present studies of interchromophore interactions under supersonic jet conditions in a large number of dinaphthyl bichromophoric molecules by measuring their laser-induced fluorescence (LIF) excitation spectra. The molecules are composed of two naphthalene chromophores connected by an n-methylene bridge. The length of the bridge was varied as a function of the number of methylene units (n = 0, 1, 2, 4, 6), of the general type NnN(i,j), were N denotes naphthalene moiety, n the number of methylene units in the bridge, and (i,j) are the or positions of the bridge at each of the chromophores. We obtained high-quality LIF spectra of these bichromophoric olecules. In the molecules N1N(2,2), N1N(1,2), N2N(2,2), and N2N(1,2), the spectrum is characterized by an intense 0–0 region, with series of low-frequency progressions. These progressions are assigned as vibrational modes of the bridge. The appearance of several series of progressions is explained either by the excitation of different chromophores (in the mixed molecules) or by the excitation of different populated conformers. The spectrum of N4N(1,1) is different in several aspects from these spectra. The origin is shifted farther to the red, to 31,402 cm^–1. Low-frequency progressions or other transitions are not observed near the origin, but typical intrachromophore naphthalene vibrations are intense. The spectra of N6N(1,1) and N6N(2,2) are also characterized by intense intrachromophore vibrations, however, the spectrum of N6N(2,2) is very complicated due to many populated conformations, while that of N6N(1,1) is more simple.     

New interpretation of experiments on the intermediate meson

A new theory of weak interactions is proposed in which the coupling between theV-A currents j(X) and j(X) is achieved not by vector mesons [by a propagator D ^c (X-X)], but by a scalar functionR(X – X), a fermion-antifermion loop which plays the role of a unique film joining two different pointsX andX of completely uncoupled space-times (as a result of which the space becomes a continuum). The existence of the actual currents j results from correlations between the two different spinor layers of Dirac layer formation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 25–40, February, 1996.     

Observation of new laser transitions and saturation effects in optically pumped NO

We report investigations of an NO laser employing specially profiled magnetic fields of up to 3.4T, and F₂ pump laser intensities as great as 20 MW cm^–2. We have observed laser oscillation at 226 nm on a rotational branch of the B'-X/it(3–11) band of NO for the first time, in addition to the previously reported oscillation at 218 nm on the B'-X/it(3–10) band. We have also observed visible laser emission on a rotational branch of the B ²-B ² II(3–1) band of NO. Saturation of the NO laser pulse energy with pump intensity has been observed, the total NO laser pulse energy having been increased to 490 J. The possibility of increasing the NO laser pulse energy towards 1 mJ per transition is discussed.     

Motion picture x-ray diffraction investigation of the martensitic transformation in nickel-titanium alloy

The thermoelastic martensitic transformation of an equiatomic nickel-titanium alloy is investigated by means of x-ray diffraction motion pictures using synchrotron radiation. The x-ray patterns are recorded by a parallel detector simultaneously in the range of angles 2=34°–51° at a wavelength of 1.4879 Å during heating and cooling with good temperature resolution. The basic parameters of the attendant B2, R, and B19 phases are determined simultaneously and compared. The variations of the parameters of the martensite B19 unit cell are traced, along with the evolution of the R phase {202}{202} reflection doublet during transformation. Volumetric transformation phenomena are determined, and it is shown that martensite originates in a more unconsolidated structure than in the equilibrium state.Institute of Physics of Strength and Materials Science, Siberian Branch, Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 49–54, August, 1994.     

Quantum-resolved fluorescence excitation spectra of SnO free radical

TheA ¹ –X ^{1 +} system of SnO is studied by laser- induced fluorescence excitation spectroscopy using isotopically enriched tin Sn¹¹⁶. The rotational structure analysis has been carried out for 6-0, 5-0, 2-0 bands. All these spectra were well resolved only with few perturbed lines in 2-0 band. Rotational constantsB ₂,B ₅,B ₆ and henceB _e , _{e e} have been obtained for the Sn¹¹⁶O molecule. An extension of perturbation study on 4-0 band has been made showing the maximum perturbation occurs at different J values for different isotopes.     

Motion of vortex lines and mutual friction in superfluid4He nearT λ

The motion of a single vortex line in superfluid⁴He nearT is studied within modelF. The linear response of the vortex-line velocityv _L to a homogeneous counterflowv _s –v _n is calculated up to lowest order of renormalized perturbation theory. The critical temperature dependence is taken into account via the renormalizationgroup theory. Non-asymptotic critical effects are found to be important. The results are generalized to describe collective vortex motion and mutual friction in rotating superfluid⁴He. The phenomenological mutual-friction coefficientsB andB of Hall and Vinen are determined without adjustment of parameters. ForB quantitative agreement with experiments nearT is found whereas forB the agreement is only semiquantiative.