Strain Concentration Effect in Cu–Al–Ni Single Crystals under a Longitudinal Bending Force

The behavior of a superelastic Cu?14.2% Al?4%Ni single crystal in the case of high reversible strains under a longitudinal bending force was investigated. The effect of strain confinement along the crystal length was revealed and studied. The highest reversible strains (up to 10%) were shown to be confined within the central part of the bent crystal.     

The burst character of thermoelastic shape-memory deformation in crystals of Cu-Al-Ni alloys

We have revealed and investigated the burst character of shape-memory deformation (SMD) in crystals of Cu-13.6 wt % Al-4.0 wt % Ni alloys. We have found that, after giving SMD to 8% when compressed in the direction of the [100] axis and subsequent heating on the solid base with an additional weight of 400 g, the system can rebound up to a height of 55 mm at a speed of ≈1 m/s. The calculations showed that, in the absence of load, a crystal with a weight of 0.8 g (in on absence of air friction) can rebound to a height of 27.5 m with a velocity of 23 m/s when rising from the base. The mechanism of such an unusual behavior of shape-memory deformation in this alloy was studied.     

Microhardness and Crack Resistance of Gallium Oxide

Technical Physics Letters - The microhardness and crack resistance of two main gallium oxide polytypes: metastable α-Ga2O3 with a corundum structure and β-Ga2O3 (high-temperature phase)...     

On a reduction in cracking upon the growth of AlN on Si substrates by hydride vapor-phase epitaxy

The main problem of the epitaxial growth of thick AlN layers on a Si substrate consists in the formation of cracks, which complicates the application of structures of this kind in the fabrication of semiconductor devices. The possibility of obtaining crack-free AlN layers with a thickness exceeding 1 μm and a mirror- smooth surface by hydride vapor-phase epitaxy is demonstrated. The properties of the layers are studied by X-diffraction analysis, optical and scanning electron microscopy, and Raman spectroscopy.     

Surface modification/alloying using intense pulsed electron beam as a tool for improving the corrosion resistance of steels exposed to heavy liquid metals

The alloying of steel surface with aluminum (Al) using Microsecond-pulsed Intense Electron Beams (MIEB-Al) was developed and optimized in order to be used for improving the corrosion resistance of the 316, 1.4970 and T91 steels, exposed to liquid Pb and Pb-Bi-eutectic. The procedure consists in two steps: (i) coating the steel surface with Al or an Al-containing alloy layer and (ii) melting the coating layer and the steel surface layer using intense pulsed electron beam. In order to cover the steel surface with an homogeneous and crack-free Al-alloyed layer, the following experimental conditions are required: Al coating thickness range 5-10 μm, electron kinetic energy 120 keV; pulse duration 30 μs; energy density 40-45 J/cm²; number of pulses 2-3.Using the mentioned procedure, the corrosion resistance of the 316, T91 and 1.4970 steels, exposed to Pb and Pb-Bi-eutectic with different oxygen concentrations and under different temperatures, was considerably improved due to the formation of a thin alumina layer (which thickness is lower than 1 μm for all the tested temperatures and durations) acting as an anti-corrosion barrier.     

Interfacial Stresses and the Anomalous Character of Thermoelastic-Deformation Curves of a Cu–Al–Ni Shape-Memory Alloy

Thermoelastic-deformation curves of a single-crystalline Cu–13.5 wt % Al–4.0 wt % Ni shapememory (SM) alloy have been studied. Cyclic temperature variation in a 300–450 K interval revealed an anomalous character of thermoelastic hysteresis loops with regions of accelerated straining at both heating and cooling stages. The observed phenomenon can be used for increasing the response speed of SM-alloy based drive and sensor devices. Analysis of this phenomenon in the framework of the theory of diffuse martensitic transformations showed that the anomalous character of thermoelastic hysteresis loops may be related to the influence of interfacial stresses on the dynamics of martensitic transformations in these SM alloys.     

Thick α-Ga2O3 Layers on Sapphire Substrates Grown by Halide Epitaxy

Semiconductors - This work reports on the epitaxial-film growth and characterization of a new wide-gap semiconductor α-Ga2O3. Layers are deposited by chloride vapor phase epitaxy on sapphire...