Danuta Stróż

Two-stage martensitic transformation in a deformed and annealed NiTi alloy

Deformation and subsequent annealing of NiTi alloys offers great possibilities of controlling characteristic temperatures, sequences of transformations and shape recovery. Todoroki and Tamura showed that depending on annealing temperatures, changes in transformation sequences in deformed alloys occur during both heating and cooling. They also observed that the cooling DSC (Differential Scanning Calorimetry) curves exhibit two peaks in the range of the martensitic transformation for specimens annealed at 500 C. Referring to the paper of Monasevich and Pascal they explained this effect as the formation of two types of martensite. In this paper the authors try to prove that the appearance of two peaks in the martensitic range on the DTA (Differential Thermal Analysis) cooling curves may be due to changes of dislocation configuration caused by the low-temperature annealing.

Effect of early stages of precipitation and recovery on the multi-step transformation in deformed and annealed near-equiatomic NiTi alloy

Abstract Multi-step martensitic transformation in Ni50.6at.%–Ti alloy was studied by means of differential scanning calorimetry and electron microscopy methods. The alloy was subjected to 10% deformation after solution treatment and then annealed at 673 K for different times. The time evolution of the multi-step transformation is explained in terms of the complex alloy structure and non-homogeneity of the precipitate distribution in the matrix.

Ferroelectric properties of ultrasonochemically prepared SbSI ethanogel.

This article presents for the first time the electrical properties of sonochemically synthesised, high-surface-area SbSI ethanogel made up of large quantity nanowires with lateral dimensions of about 10-50 nm and lengths reaching up to several micrometers. The composition, morphology, dimensions, microstructures, and optical energy gap of the new form of SbSI were characterized. This material is a semiconducting ferroelectric as in the case of bulk SbSI crystals. The maximum of dielectric constant epsilon=1.6x10(4) is observed at Tc=292(1) K. The activation energies in temperature dependences of electric conductivity of SbSI ethanogel are different for ferroelectric and paraelectric phases during heating and cooling of the sample.

Structure and properties of melt-spun Cu–Al–Ni shape memory alloys

Abstract Increase of the wheel speed causes the grain refinement, rise of a columnar morphology of grains and the DO 3 fibre texture in the melt-spun ribbons of the studied alloys. This influences their tensile strength, yield stress and shape recovery under load. Additional possibilities of influencing the structure and hence the properties of the ribbons open up for the alloys containing Ti+Mn by presence of particles of the X -phase as well as by recrystallisation. The ribbons of the studied alloys melt-spun with the wheel speed up to 20 m/s exhibit a relatively high transformation temperature.

Sonochemical preparation of SbS1−xSexI nanowires

A sonochemical method for direct preparation of nanowires of SbS(1-x)Se(x)I solid solution has been established. The SbS(1-x)Se(x)I gel was synthesized using elemental Sb, S, Se and I in the presence of ethanol under ultrasonic irradiation (35kHz, 2W/cm(2)) at 50 degrees C for 2h. The product was characterized by using techniques such as powder X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive X-ray analysis, selected area electron diffraction, and optical diffuse reflection spectroscopy. The SEM and HRTEM investigations exhibit that the as-prepared samples are made up of large quantity nanowires with lateral dimensions of about 10-50nm and lengths reaching up to several micrometers and single-crystalline in nature. The increase of molar composition of Se affects linear decrease of the indirect forbidden optical energy gap as well as the distance between (121) planes of the SbS(1-x)Se(x)I nanowires.

Sonochemical growth of antimony sulfoiodide in multiwalled carbon nanotube.

This paper presents for the first time the nanocrystalline, semiconducting ferroelectrics antimony sulfoiodide (SbSI) grown in multiwalled carbon nanotubes (CNTs). It was prepared sonochemically using elemental Sb, S and I in the presence of methanol under ultrasonic irradiation (35kHz, 2.6W/cm(2)) at 323K for 3h. The CNTs filled with SbSI were characterized by using techniques such as powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, high-resolution transmission electron microscopy, selected area electron diffraction, and optical diffuse reflection spectroscopy. These investigations exhibit that the SbSI filling the CNTs is single crystalline in nature and in the form of nanowires. It has indirect forbidden energy band gap E(gIf)=1.871(1)eV.

Sonochemical preparation of SbSeI gel

A novel sonochemical method for direct preparation of nanocrystalline antimony selenoiodide (SbSeI) has been established. The SbSeI gel was synthesized using elemental Sb, Se, and I in the presence of ethanol under ultrasonic irradiation (35 kHz, 2W/cm(2)) at 50 degrees C for 2h. The product was characterized by using techniques such as powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and optical diffuse reflection spectroscopy (DRS). The SEM and HRTEM investigations exhibit that the as-prepared samples are made up of large quantity nanowires with lateral dimensions of about 20-50 nm and lengths reaching up to several micrometers and single crystalline in nature.

Influence of the solvent on ultrasonically produced SbSI nanowires

The influence of the substitution of methanol in place of ethanol during the ultrasonic production of antimony sulfoiodide (SbSI) nanowires is presented. The new technology is faster and more efficient at temperatures greater than 314 K. The products were characterized by using techniques such as powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDXA), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), optical diffuse reflection spectroscopy (DRS) and IR spectroscopy. The coexistence of Pna2(1) (ferroelectric) and Pnam (paraelectric) phases at 298 K was observed in the SbSI nanowires produced in methanol. The methanol decomposes during the sonication or due to the adsorption process on SbSI nanowires.

Sonochemical preparation of antimony subiodide

The substantiated isolation of the antimony subiodide (Sb(3)I) is presented for the first time. It has been prepared using elemental Sb and I in ethanol under ultrasonic irradiation at 323 K. Its composition was characterized using X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray analysis (EDAX). The scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) investigations exhibit that the samples are made up of large quantity of nanoparticles with diameters smaller than 20 nm and single crystalline in nature. The interplanar spacings in Sb(3)I that have been determined using powder X-ray diffraction (XRD), selected area electron diffraction (SAED) and HRTEM are very similar. Surprisingly, the registered XRD patterns are identical to the one reported earlier for Sb(4)O(5)I(2).

Structure and Properties of Cold-Worked and Annealed Ti-Ni-Co Shape Memory Wires Designed for Medical Application

The effect of plastic deformation by drawing and rolling in the martensite state and final annealing on the structure, grain size, martensitic transformations and shape memory properties of TiNiCo wires is described in the paper. The wires were cold worked by 30 and 40% and then annealed at the temperature range 300-600oC. The structure, phase composition and transformation behaviour of samples after processing and annealing were studied using transmission electron microscopy (TEM), X-ray diffraction (XRD) method and differential scanning calorimetry (DSC) technique. The marformed and annealed at 400 and 450oC wires exhibited a very good superelastic behaviour. The obtained wires were used for production of the shape memory staples with the recovery temperatures close to the human body temperature and as well as for small superelastic staples for fixation of mandible bone fractures.