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The cyclic stability of superelasticity in compression in [001]B2-oriented Ti49.3Ni50.7 single crystals is considered in this paper. The crystals were aged at 823 K for 1.0 h in air and helium. It has been experimentally shown that a two-layered surface thin film, consisting of a Ni-free oxide layer and a Ni-rich sublayer, appears after the oxidation at 823 K in air. The surface layers have a weak effect on the forward B2-R-B19’ martensitic transformation temperatures: TR temperature increases by 4 K; Ms and Mf temperatures decrease by 6 K. The oxide layer does not affect either the superelasticity response during fatigue tests or the temperatures of reverse B19’-B2 martensitic transformation. The cracking of the surface oxide layer during fatigue tests was not found in [001]B2-oriented single crystals aged in air. This is contributed by the relaxation of internal stresses. Such internal stresses are caused by both the formation of an oxide layer during aging and the matrix deformation at the stress-induced martensitic transformation. The main relaxation mechanisms of the internal stresses are the oriented growth of Ti3Ni4 precipitation near a thin surface film at aging in air, the formation of dislocations near the precipitation-matrix interface and a fine twinned B19’-martensite at fatigue tests.

A high-temperature water steam (H2O(g)) between 300 °C and 1000 °C reacted with the Al surface in this study. The Al surface states were characterized and analyzed using XRD °C, XPS, and SEM after and before the reaction, and the effects and mechanism of H2O(g) on the Al surface morphology and chemical composition were studied. The experiment showed that for an Al sheet reacting with H2O(g), its oxide layer morphology changed from nano-needle to flaky and granular oxides gradually with the rise of temperature, and finally the Al surface became porous as a whole. Its oxide crystals were amorphous and were determined to be aluminum oxide (Al2O3) using XPS. The needle-like oxide in the Al sheet surface tended to grow toward the surface, and no obviously inward oxidizing corrosion layer occurred in the aluminum substrate; the oxide layer between the oxide and Al sheet substrate was compact, and could effectively prevent the infiltration and corrosion of water molecules.

Magnesium (Mg) alloys possess the lowest density among structural materials, and their application in the automotive and aircraft industries might enhance fuel efficiency. The mechanical properties can be improved by the addition of alloying elements. However, since Mg and its alloys are very susceptible to corrosion degradation, it is important to study the effect of these elements on the alloys’ corrosion behavior. In this study, 1 wt% of calcium (Ca) was added to wrought AM60 Mg alloy, and the electrochemical corrosion behavior of the alloys in alkaline solutions with and without Cl− ions was compared. The corrosion behavior was investigated by means of immersion tests, gravimetric measurements and potentiodynamic polarization (PDP); the characteristics of the oxide layer were studied by electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). The addition of Ca resulted in precipitation of the ternary aluminum-rich (Mg-Al)2Ca phase. Scanning Kelvin probe force microscope (SKPFM) identified that this phase has a cathodic behavior relative to the α-Mg matrix; hence it can serve as additional sites for initiation of pitting corrosion. As a result, the corrosion resistance of wrought AM60 alloy with 1 wt% Ca addition deteriorated in a NaCl solution. However, in the absence of Cl− ions, alloying with Ca improves the corrosion resistance of wrought AM60 alloy due to the stabilization of the corrosion products layer. The effect of long-period immersion time on the corrosion behavior and alloy oxidation is discussed.

Currently, surface treatments lead to inducing a superficial layer of several nanometers up to micrometer, which in some cases can be protective. In this experimental work, an oxide layer was generated under different atmospheres (CO2 and steam atmospheres) during the thermal aging treatment of two different maraging grades, 300 and 350. Afterwards, this layer was microstructural and mechanically characterized by advanced characterization techniques at the micro- and submicron length scale to highlight some information related to the generated oxide layer. The results showed that the oxide layer (in both grades) was made up of several compounds like: TiO2, MoO3, hematite (α-Fe2O3), and CoFe2O4, this being the majority compound distributed homogeneously throughout the layer. Furthermore, a nickel-rich austenitic phase at the interphase was mainly made up cobalt ions (Co2+), instead of iron ions (Fe2+), within the spinel lattice.

Laser cleaning is a competitive alternative to ablate and remove the hard oxide layer on hot-rolled stainless steel. To meet the practical demand, laser-induced breakdown spectroscopy (LIBS) was applied for real-time monitoring of the cleaning process in this study. Furthermore, the as-received and laser cleaned surfaces were characterized by an optical micrograph, an X-ray diffractometer, and a laser scanning confocal microscope. The results showed the relative intensity ratio (RIR) of the FeI emission line at 520.9 nm and the CrI emission line at 589.2 could be a quantitative index to monitor the cleaning process. When the oxide layer was not fully cleaned, the LIBS signals of the substrate were not excited, and the ratio was almost invariant as the power of the laser increased. However, it sharply increased once the oxide layer was effectively cleaned, the cleaned surface was bright, and the surface roughness was smaller in this case. Subsequently, as the surface was over-cleaned with the further increase of laser power, the RIR value remained large. The optimal laser cleaning parameters obtained by the monitoring were determined to avoid re-oxidation and reduce the roughness of the cleaned surface.

The article presents a detailed study and characterization of the oxide layers on the surface of iron particles of various sizes. Ten iron samples with a size range from a few nm to 50 µm were studied in detail using SEM, TEM, XRD, and TGA analysis. The composition of the multiphase oxide layers on the powder surface was investigated. The main components of the oxide layer were FeO, Fe3O4, and Fe2O3. By the obtained data, a model for the calculation of a multiphase oxide layer thickness on the surface of iron particles was proposed. The proposed model was validated and can be used for the characterization and certification of micro– and nanoscale iron particles.

In this study, dieless drawing experiments of stainless steel SUS304 wires of 1 mm in diameter were carried out using a self-developed dieless drawing machine. In order to prevent oxidation, argon gas was applied to a self-designed chamber during dieless drawing processes. The effects of the forming temperature and the oxide layer on the mechanical properties of the drawn SUS304 stainless wires obtained by tensile tests are discussed in this paper. A finite element model considering the high frequency induction heating mode in the finite element software DEFORM2D was developed to conduct the heat transfer analysis and the formability analysis of the drawn products in dieless drawing of stainless steel wires. The effects of the drawing speed and forming temperature on the maximal reachable area reductions are discussed. Through the comparisons of the maximal reachable area reduction between the finite element simulations and experiments, the finite element modelling for dieless drawing processes was validated.

Yttria-tetragonal zirconia polycrystal (Y-TZP) is a difficult substrate to bond to due to the absence of a glass phase and the material’s chemical inertness. This study evaluated the effect of two monomers for metal, MDP (10-methacryloyloxydecyl dihydrogen phosphate) and VBATDT (6-(4-vinylbenzyl-n-propyl)amino-1,3,5-trizaine-2,4-dithiol) on bond strength to Y-TZP. Seven combinations with different concentrations of MDP and VBATDT-monomers (0.0, 0.1, 0.5, or 1.0 wt %) in acetone solution were developed and applied to the surface of Y-TZP slabs, which were bonded to composite resin substrates using a resin cement under standard loading. Non-primed samples were used as controls. Bonded specimens were cut for microtensile testing and tested after either 48 h or 180 days in water storage at room temperature. All samples from control group (no primer) and MV5 group (0% MDP/0.5% VBATDT) debonded spontaneously. Two-way ANOVA showed that the primer had a significant effect (p < 0.001) on bond strength to zirconia, whilst storage time did not (p = 0.203). Tukey HSD (honest significant difference) test indicated that groups with at least 0.5% of each monomer resulted in higher initial bond strength values. Although chemical bonding to zirconia is credited to MDP, a correct balance between MDP and VBATDT may imply in better bond strength results. The minimum concentration of each monomer should not be lower than 0.5 wt %.