Superelasticity in high strength heterophase single crystals of Ni51.0Ti36.5Hf12.5 alloy

The effect of precipitated disperse H-phase particles on the thermoelastic B2–B19′ martensitic transformation (MT) under compressive load has been studied on [001]-, [236]-, and [223]-oriented single crystals of Ni51.0Ti36.5Hf12.5 (at %) alloy in the initial (as-grown) state. It is established that, in Ni51.0Ti36.5Hf12.5 single crystals containing disperse H-phase particles with dimensions within 125–150 nm at a volume fraction of ~30%, neither the critical stresses of martensite formation nor superelasticity strain depend on the orientation. Fully reversible B2–B19′ MTs in Ni51.0Ti36.5Hf12.5 single crystals have been observed in tests at external axial stresses up to 1700 MPa and temperatures up to Tt ~ 373 K

Techniques for the analysis of total energy and labor of industrial plants / CAC No. 198

Bibliography: p. 24

Mechanical Oscillations in TiNi Under Synchronized Martensite Transformations Experimental Procedure

Mechanical vibrations in alloys with thermoelastic martensitic transformations have some specific features. The main one is the existence of damping peaks at temperatures of austenite<-*martensite transitions (Van Humbeeck, 1989; Naturally, experiments including fast phase transformations with the duration of a small fraction of the period of vibrations (when tpi, < T) do not allow correctly judging the internal friction as of material damping capacity. However, such experiments are interesting from the point-of-view of active control of vibrations by fast changes of the phase composition. When tph < T, the object under investigation must be considered as a solid with periodically varying strain, in which martensitic transformation occurs on some stages of the deformation. In TiNi-based alloys the transformation is accompanied with such phenomena of martensitic nonelasticity as shape memory, transformation plasticity, generation, or relaxation of stresses. In other words, it leads to a change of the stressedstrained state of the body. If such changes occur one or several times during one period of vibrations, they will necessarily influence the whole mechanical process and cause a variation of the amplitude and frequency of vibrations, level of damping. The result of such influence will certainly depend on what stage of a vibration period the transformation takes place, is it direct or reverse, etc. On the whole, the existing knowledge of martensitic nonelasticity allows us to state that an effective control of vibrations can be achieved by specially organized fast changes of the material structural state. This is confirmed by the results of the preliminary studies by The main goal of this work is the analysis of the influence of fast martensitic transformations on the unforced oscillations of a TiNi alloy wire torsional pendulum. Experimental Procedure The vibrating system under investigation was a torsional pendulum. The specimen used as a working body has been made of Ti-50at.%Ni wire with the length 400 mm and the diameter 0.5 mm. After annealing the alloy had the transformation temperatures Af, = 330 K, Mf = 320 K, A, = 355 K, Af = 370 K. At the room temperature the specimen had the structure of martensite. The upper end of the specimen was fixed in an unmovable conical grip and the lower end could rotate freely together with an attached beam with weights. The length of the beam and the mass of weights have been chosen because the frequency of pendulum vibrations was about 0.05 Hz. The beam was equipped with a transparent rim with scores. Pendulum rotation by one angular degree corresponded to an interval between the scores. The angle of rotation was measured by the number of scores which passed through an optical registration system consisting of a lamp, a collimator, and a photo-indicator. Heating of the specimen had been done by the passing of alternating current through the circuit: upper grip-specimensteel rod fastened to the lower grip and aligned along the pendulum axis-electrolyte (water solution of copper sulfate) -copper blade contact immersed into the electrolyte. The use of the electrolytic bath as part of the circuit allowed securing a reliable electric contact with the specimen and reduce friction to a minimum. Cooling of the specimen after the break of the current occurred by natural heat exchange with the air. The mean temperature was obtained by measuring the resistivity of 0.01 mm diameter copper wire coiled around the specimen on all its length. The deformation y of the specimen was calculated by the formula y = irip)/L, where r and L are radius and length of the specimen, tp is the rotation angle in radians. The initial angular deflection of the pendulum from equilibrium corresponded to 7o = 0.3% deformation. Martensitic transformation was provoked by heating of the specimen with 0.2 s impulses of 3.5 A current. During an impulse the specimen was transformed from martensitic state into an austenitic one. Synchronization of the impulses with the mechanical oscillations is illustrated by Heating impulses were applied at a frequency twice that of the vibrations and as one may see from the figure the specimen experienced the transition from martensite to austenite and back in the course of each semiperiod of the vibrations. The moment of time corresponding to the maximum deflection of the pendulum from equilibrium in each semiperiod was registered by the equipment (by the minimum of the angular speed of the beam) and in a specified delay time At a heating impulse was given

Mitochondrial carrier homolog 1 (Mtch1) antibodies in neuro-Behçet's disease

Cataloged from PDF version of article.Efforts for the identification of diagnostic autoantibodies for neuro-Behcet's disease (NBD) have failed. Screening of NBD patients' sera with protein macroarray identified mitochondrial carrier homolog 1 (Mtch1), an apoptosis-related protein, as a potential autoantigen. ELISA studies showed serum Mtch1 antibodies in 68 of 144 BD patients with or without neurological involvement and in 4 of 168 controls corresponding to a sensitivity of 47.2% and specificity of 97.6%. Mtch1 antibody positive NBD patients had more attacks, increased disability and lower serum nucleosome levels. Mtch1 antibody might be involved in pathogenic mechanisms of NBD rather than being a coincidental byproduct of autoinflammation. © 2013 Elsevier B.V

The Diagnostic Utility of Maspin in the Distinction between Malignant Mesothelioma and Pulmonary Adenocarcinoma

Immunohistochemistry is frequently employed to differentiate between malignant mesothelioma (MM) and pulmonary adenocarcinoma (AC) infiltrating the pleura, but there is uncertainty as to which antibodies are most useful. The present study investigated the presence of the serine protease, maspin, in epithelioid MMs and evaluated the diagnostic utility of maspin for the differential diagnosis between epithelioid MM and pulmonary AC with pleural involvement. The results showed more frequent maspin immunostaining among AC cases compared with MM cases. Maspin positivity was significantly higher among AC cases with respect to both the extent and intensity of staining. A significant difference also existed between the two tumour types with respect to the overall maspin score. Despite these findings, the sensitivity and specificity of maspin positivity to detect AC were only 59% and 73%, respectively, indicating that detection of maspin is of no value for the differential diagnosis of AC and MM

High-temperature functional behavior of single crystal Ni51.2Ti23.4Hf25.4 shape memory alloy

In this work the functional behavior of the new Ni51.2Ti23.4Hf25.4 high temperature shape memory alloy is investigated along three crystal orientations in compression and compared with the polycrystal behavior. Transformation temperatures were measured following specific aging treatments with the aim to optimize the shape memory and pseudoelastic behaviors. Two aging treatments were then selected in order to fulfill the optimum pseudoelastic behavior (500°C/4 h), and the maximum transformation temperatures (550°C/10 h) without compromising the alloy functionality. High temperature X-ray diffraction was utilized to determine the crystal orientations in the austenite phase for the single crystal specimens. The martensite structure was found to be the B19 orthorhombic, in contrast with monoclinic structure for lower Hf contents. Digital image correlation was successively used during isobaric strain-temperature experiments on the single crystal and polycrystal specimens. Large strain heterogeneities were found for the single crystals which pair with X-ray diffraction data that show un-transformed austenite below the martensite finish temperature. This reveals the heterogeneity of the austenite–to–martensite transformation for the present NiTiHf alloy which explains the divergence between the theoretical and experimental transformation strains. In addition, using digital image correlation it is possible to capture the local strain fields associated with fully transformed specimen regions. The transformation strains calculated locally are in close agreement with the theoretical transformation strains calculated with lattice deformation theory for the cubic austenite to the orthorhombic martensite phase transformation