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Ceria-based Al2O3 composite electrolytes were prepared using (CeO2)0.6(SmO1.5)0.2(GdO1.5)0.2 (C6S2G2) and Al2O3 powders, employing sol-gel and low temperature combustion synthesis methods (SGLCS). The influence of Al2O3 content on the sintering behavior and electrical properties was studied. The results showed that electrical properties could be improved by adding 10wt% Al2O3. The sintered density was up to 5.61g/cm3. Most measurements of open circuit voltage (OCV) ranged between 0.8 and 1.2V; an OCV value of 1.15V was obtained at 370oC. The performance of intermediate- temperature solid oxide fuel cells (ITSOFCs) with a properly Al2O3 doped electrolyte was better than when a pure ceria-based one was used. The highest power density was 200mWcm-2.

Abstract: Ceramic ZrO2 and metallic Ti–6Al–4V alloy are jointed by using a Ti33Zr17Cu50 (at.%) amorphous alloy as a solder at 1123–1273K in a high vacuum. It is demonstrated that the microstructure and mechanical properties are significantly influenced by the brazing temperature, the heat time and the cooling rate. The brazing seam jointing ZrO2 with Ti–6Al–4V is composed of ZrO2/Cu2Ti4O, (Ti,Zr)2Cu/TiO, Ti2O/CuTi2, (Ti,Zr)2Cu/CuTi2/Ti–6Al–4V alloys and compounds, of which the increasing thickness weakens the shear strength as the brazing temperature, the heat time the cooling rate increase. The maximum shear strength of the brazing joints reaches 162MPa with the optimal technical parameters: the brazing temperature of 1173K, the heat time of 10min and the cooling rate of 5K/min. The fracture of the joint occurs in the brittle seam layer nearby the side of ZrO2. [Copyright &y& Elsevier]

Abstract: Laser alloying of Ni–P electroless deposited layer with aluminum substrate was carried out by Nd–YAG pulsed laser. The phase composition and microstructure of the alloyed layers produced by different laser power densities were identified by X-ray diffractionary (XRD), scanning electron microscope (SEM) accompanied by energy dispersion X-ray analysis (EDS) and transmission electron microscope (TEM). Furthermore, the surface roughness of the alloyed layers was characterised by confocal laser scanning microscope (CLSM). The results showed that the characteristic dendritic or lamellar microstructures were observed in the alloyed layers. The phase constituents of the alloyed zones were intermetallic compounds of nickel–aluminum NiAl, Al3Ni and Al3Ni2, as well as some non-equilibrium phases and amorphous phases depending on the employed laser power density. As a result, the microhardness of the alloyed layer with Ni–P amorphous phases formed at laser power density 5.36×109 W/m2 reached to HV0.1 390. [ABSTRACT FROM AUTHOR]

Abstract: In this study, results in the irradiation of stainless steel AISI 304 in air with nanosecond laser pulses at laser irradiation power density 4×107 W/cm2 are reported. Laser processing parameters, such as wavelengths 532 and 1064nm, pulse duration 20ns and repetition rate 10Hz were used. It is shown that the surface morphology of the stainless steel is related to the number of pulses applied to the same spot. The following surface morphological changes were observed: (i) occurrence of the micro-grains microstructures at wavelengths 532 and 1064nm after 10000 pulses irradiation and (ii) occurrence of vermiform-like microstructures at wavelength 1064nm after 1000 pulses irradiation. Generally, it is concluded that irradiation due to several consecutive pulses caused significant damage and enhanced the stainless steel surface roughness. [Copyright &y& Elsevier]

Abstract: TiC/Ni3Al composites have been obtained in situ by laser ignited self-propagating high-temperature synthesis (LISHS) of an intimate mixture of compacted powders of elemental C, Ti, Ni and Al. Ignition temperature (T ig) and combustion temperature (T c) are investigated; the effects of Ni3Al content on density, phase composition, microstructure of the reaction products and particle size of the synthesized TiC were studied. The results show the density of the products varies with Ni3Al content, and a maximum value of density appears at 50wt.% Ni3Al; TiC and Ni3Al are the two stable phases after SHS, TiC particle size decreases with the increasing of Ni3Al content, however, the decreasing of grain size is unobvious when Ni3Al content is over 60wt.%. [Copyright &y& Elsevier]

Abstract: TiC/Al composite was successfully synthesized utilizing laser ignited self-propagating high-temperature synthesis (SHS) of Al–C–Ti system with the different C/Ti molar ratio. When the molar ratio of C to Ti is below 1:1 in the starting materials, in addition to fine TiC particulates, a large amount of Al3Ti phase was found in the composites; however, when the molar ratio of C to Ti is 1:1 in the starting materials, the Al3Ti phase was almost completely eliminated and the distribution of TiC particulates generally appeared to be more homogeneous throughout the products synthesized. [Copyright &y& Elsevier]

Abstract: The effects of laser surface melting (LSM) on microstructure of magnesium alloy containing Al8.57%, Zn 0.68%, Mn0.15%, Ce0.52% were investigated. In the present work, a pulsed Nd:YAG laser was used to melt and rapidly solidify the surface of the magnesium alloy with the objective of changing microstructure and improving the corrosion resistance. The results indicate that laser-melted layer contains the finer dendrites and behaviors good resistance corrosion compared with the untreated layer. Furthermore, the absorption coefficient of the magnesium alloy has been estimated according to the numeral simulation of the thermal conditions. The formation process of fine microstructure in melted layers was investigated based on the experimental observation and the theoretical analysis. Some simulation results such as the re-solidification velocities are obtained. The phase constitutions of the melted layers determined by X-ray diffraction were β-Mg17Al12 and α-Mg as well as some phases unidentified. [Copyright &y& Elsevier]

Highlights: [•] Oxidation phenomenon in one laser spot on stainless steel surface is studied. [•] Compositions and morphologies vary from center to edge in one laser spot. [•] Hexagonal Cr2O3 distributes in the edge, while spherical Fe2O3 in the center. [•] Oxidation mechanism is proposed based on thermodynamics and kinetics. [Copyright &y& Elsevier]

Abstract: The butt welding of 304 stainless steel plates with thickness of 3mm and 6mm were achieved by YLR-6000 fiber laser under Ar protective gas. The weld appearance, microstructure, composition distribution and microhardness of welded joint were emphatically investigated. The results showed that the narrow and fully penetrated welded joint without marco-defects can be obtained with tightly focused 2kW fiber laser power and 20mm/s welding speed. The weld bead was smooth, and various microstructures typically formed at different zones of the welded joint. The fine columnar and equiaxed crystals existed in the edge and center of weld bead, respectively. Both were different with the microstructure of the stainless steel substrate. However, the composition distribution of the welded joint had no obvious changes. Furthermore, the superior microhardness of welded joint over the stainless steel substrate was mainly attributed to its finer microstructure. [Copyright &y& Elsevier]

Abstract: Different laser energy densities were utilized to treat AISI 304 stainless steel via Nd:YAG pulsed laser surface melting (LSM). The surface composition and microstructure of the stainless steel were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM). In particular, the corrosion behaviors of the stainless steel surface without and with LSM were evaluated by the electrochemical polarization measurement in 3.5wt.% NaCl aqueous solution at room temperature. The results showed that the stainless steel surface without LSM suffered severe localized pitting under the testing conditions. A thin surface oxide protective layer was produced on the stainless steel surface with LSM, which considerably improved the corrosion resistance properties of the stainless steel. The height differences of the corrosion regions on the stainless steel surface with LSM were measured to establish more corrosion resistant region, using scanning confocal laser microscopy. The underlying corrosion mechanism of the stainless steel with LSM was revealed. [Copyright &y& Elsevier]

Abstract: Experiments were conducted to study the microstructure and tensile properties of the sub-micro and nano-structured Al produced by the Nd:YAG pulsed laser surface melting (LSM). The surface and longitudinal section microstructures of the Al samples after LSM were analyzed. The solidification microstructures in the LSM region were very fine which was beneficial to improve the properties of the Al sample. The tensile behavior and the relevant fracture mechanism of the LSM layer on the Al surface were investigated based on the analyses of the tensile test results. The fracture morphologies in the LSM region were small and shallow dimples with the size of 0.4–1μm. It indicated that the Al sample showed the ductile behavior because the grains were refined effectively after LSM. Furthermore, the typical amorphous fracture morphology with the fish scale structure was also obtained at the strain rate of 1.0×10−4 s−1 after LSM with the laser power density of 3.65×109 W/m2. [ABSTRACT FROM AUTHOR]

Abstract: The laser surface melting (LSM) technique was adopted to modify the surface layer microstructure of the AISI 304 stainless steel in this paper. The results showed that the hexagonal morphologies have been successfully fabricated on the surface after LSM. These hexagons had side lengths of about 0.5–1μm and were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), field emission scanning electron microscope (FESEM) and high resolution transmission electron microscope (HRTEM). It was proved by the XRD that the stainless steel surface mainly consisted of γ-Fe, Cr2O3, Fe2O3 and some manganese oxides. The FESEM micrographs showed that the hexagonal oxides were regular hexagons in geometry. The HRTEM micrographs also indicated the presence of the hexagons on the surface of the stainless steel. The spacing values were calculated from the HRTEM micrograph and the SAED pattern, and the hexagonal oxide phases determined by these spacing values were consistent with those verified by the XRD. After LSM, the microhardness of the stainless steel was significantly improved. [Copyright &y& Elsevier]

Abstract: The laser surface cladding of an AZ91D magnesium alloy with Al and Al2O3 powders was investigated using a pulsed Nd:YAG laser. The optimum ratio of Al to Al2O3 and the suitable range of laser processing parameters were identified. The resulting microstructure in the modified surface layer was examined and the wear resistance property was evaluated. The results show that the wear resistance of the laser treated samples was much superior to that of the untreated samples. [Copyright &y& Elsevier]