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.     

Estimation of the Diffusion Coefficient of Doxorubicin Molecules in a Water Solution in the Volume of a Porous Carrier Medium

Russian Physics Journal - An experimental investigation of the phenomenon of diffusion of the solution components in nanosized pores is extremely difficult and in certain cases impossible. An...     

Electron phase transition in TiNi?

The optical and X-ray photoelectronic spectra and temperature dependence of magnetic susceptibility are investigated. It is found that at martensitic transformation in TiNi electron redistribution occurs which is accompanied by cardinal change of Fermi surface. Based on the data obtained in B2-structure (CsCl) E_F is assumed to lie in the kT-vicinity of the N(E) peak that determines the tendency to the structural instability of B2.     

Short-wavelength atomic-displacement modulation preceding the <Emphasis Type="Italic">B</Emphasis>2 → <Emphasis Type="Italic">B</Emphasis>19′ martensitic transformation in a TiNi-based alloy

Neutron diffraction studies of the fine structure of a Ti₄₉Ni₅₁ single crystal are performed before the onset of the B2 → B19′ martensitic transformation (temperature of the onset of the transformation M _s =200 K). Upon cooling below 460 K, extra reflections are found to form; their positions in the B2-phase reciprocal lattice correspond to the full non-Lifshitz star of the wave vector q=0.225〈112〉. At temperatures below 430 K, 0.45〈110〉 extra reflections appear, corresponding to second-order diffraction effects. In the temperature range 300–460 K, reversible and nonhysteretic changes in the intensities and positions of both types of extra reflections are observed. Analysis of the intensities and spatial distribution of the extra reflections in the B2-phase reciprocal lattice indicates that a displacive superstructure dominated by longitudinally polarized atomic-displacement waves with q=0.225〈112〉 arises in the single crystal in the pretransition temperature range.     

The structure of titanium nickelide surface layers formed by pulsed electron-beam melting

X-ray structure analysis technique has been developed for a material heterogeneous over the depth. The structure of the TiNi intermetallide subjected to surface modification by an electron beam has been investigated. The following three layers differentiated in the microcrystalline structure have been singled out: (i) the external sharply textured layer 1–3 μm in thickness with a texture in the [100] B2 direction and a lattice periodicity parameter reduced by 1% in the direction of the normal, (ii) the intermediate gradient-stressed layer 10–15 μm in thickness with the texture of the initial ingot, and (iii) the original material. The crystal lattice of the surface as well as of the intermediate layer is in a state stretched along the surface and compressed along the normal to it. This lattice distortion is maximal in the surface layer and decreases towards the bulk of the material.     

Martensite transformations in Ti-Ni alloys after long-term annealing at 773‡K

þe change in the phase composition and the temperatures and sequence of martensite transformations in Ti-Ni alloys after annealing for 100 h at 773K has been investigated by means of x-ray structural analysis and measurement of the resistivity.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 106–112, February, 1991.     

Electron properties anomalies on the stage preceding rhombohedral phase in TiNi

The qualitative change of temperature dependence of resistivity, magnetic susceptibility and peak counting rate of annihilation photons at a stage preceding rhombohedral phase in TiNi has been observed. The above anomalies of electron properties are connected with reconstruction of the electron band structure caused by charge-density-wave formation.     

Neutronographic investigation of the characteristics of phase transition in the alloy Ni3Mn,alloyed with small additions of aluminum and copper

The temperature dependence is studied of the extent of the long-range order and size of the domain in the alloy Ni₃Mn, alloyed with small additions (a few atoms percent) of aluminum and copper. It is shown that A1 stabilizes the superlattice of Ni₃Mn but Cu destroys it. In alloys of Ni₃(Mn, Al) a monotonic effect is observed of the aluminum concentration in the alloy on the nature of the phase transition.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 16–25, November, 1973.