Effects of annealing temperature on stress corrosion susceptibility of AA5083–H15 alloys were studied by annealing specimens at 150, 200, 250, 300, and 350 °C before sensitization. Nitric acid mass loss testing and slow strain rate testing were conducted to investigate intergranular corrosion (IGC) and stress corrosion cracking (SCC). Results indicate that H15 alloy was less susceptible to IGC, but this alloy had the highest susceptibility to IGC and SCC after sensitization. Due to the continuous precipitation of β phase, the sensitized 150 and 200 °C alloys were highly susceptible to IGC and SCC. The 250 °C alloy was less susceptible to IGC because of the absence of the precipitation of β phase. After sensitization, this alloy was also less susceptible to IGC and SCC on account of the discontinuous precipitation of β phase. The sensitized 300 and 350 °C alloys were susceptible to IGC but less susceptible to SCC because of their lower strength and higher elongation.

X-ray diffraction analysis, transmission electron microscopy, and thermodynamic calculation were used to investigate the effect of microstructural condition of austenite on the microstructural characteristics of the nanoscale bainite ferrite in a high carbon steel. As austenization temperature increases to 950 °C, there are a higher vacancy concentration and homogenized distribution level of the interstitial carbon atom in the austenite grains. The movement of more di-vacancies combination could encourage the generation of the γ → α embryo nucleus. The interstitial carbon atoms have a stronger inhibitory effect on the formation of the γ → α embryo nucleus and homogenized distribution of the interstitial carbon atoms are able to make the inhibitory effect exist everywhere in the austenite grains. In consequence, the bainite ferrite could only nucleate in a smaller area (several nanometers), and grow into slender laths in a smaller width and a larger length.

Cryomilling combined with laser induction hybrid cladding (LIHC) was adopted to produce NiCrAlY coatings on Ni-based superalloy. The characteristics, oxidation resistance, and mechanical properties of the cryomilled NiCrAlY coatings by LIHC were investigated. By increasing the cryomilling time, the as-received spherical powder experienced a transition from flake-shaped to polygonal structure. The particle size increased firstly and then decreased. Moreover, increasing the cryomilling time induced the columnar growth in the NiCrAlY coatings. This in turn improved the oxidation resistance and the mechanical properties of the coatings. Especially, when the cryomilling time was increased to 15 h, the oxidation resistance of the coating at 1423 K was approximately nine times than that of GH4169 superalloy. The tensile strength of the cryomilled (15 h) coating increased to 1085 MPa and the ductility was 20.7%.

Hot deformation behavior of Incoloye028 alloy was investigated by conducting hot compression tests on Gleeble-3800 simulator in the temperature range of 1223–1473 K and the strain rate range of 0.1–50 s−1. True stress–true strain curves showed that the flow stress increases with the decrease of deformation temperature and the increase of strain rate. The constitutive equations of Incoloy028 alloy were obtained by introducing Zener–Hollomom parameter, the flow behavior can be described by the hyperbolic sine function and the activation energy changes with strain rate and temperature significantly. The hot working maps of Incoloy028 alloy were proposed on basis of dynamic materials model. The hot working maps for different strains indicated that there were two instability zones, one zone is in the temperatures range of 1423–1473 K and strain rate range of 0.1–50 s−1, and another zone is in the temperature range of 1223–1423 K and strain rate range of 0.6–1 s−1. The reasonable hot working temperature range is 1423–1473 K when strain rate is more than 50 s−1.

The microstructure evolution of a typical nickel-based superalloy was studied in the temperature range of 960–1160 °C with the strain rate of 0.001 s−1 by using electron backscattered diffraction technique. Based on the grain orientation spread method, the dynamic recrystallization (DRX) grains were distinguished from the deformed grains. The results revealed that the volume fraction and the size of DRX grains increased with the increasing deformation temperatures. Most of the original Σ3 boundaries lost their twin characteristics due to crystal rotations during hot deformation. Meanwhile, lots of new Σ3 boundaries were formed in the DRX grains mainly by growth accidents. Moreover, the deformation temperature had a similar effect on the fraction of Σ3 boundary and the Σ3 boundary density in the DRX domains, which increased firstly and then decreased with the increasing deformation temperature. The Σ3 boundary density was analyzed as a function of grain size, and the critical grain size below which no twin forms was calculated to be 2.06 µm. In addition, the coherent Σ3 boundaries were easier to form at the higher deformation temperature due to their lower boundary energy.

Three isothermal sections of the Ni–Fe–Zr ternary system at 1000, 1100, and 1200 °C were experimentally determined using equilibrated ternary alloys. No ternary compound is found in this system. The obtained experimental results show that among three isothermal sections, the (γFe, Ni) phase region extends from the Ni-rich corner to the Fe-rich corner, and the solubility of Zr in the (γFe, Ni) phase is small. The phase equilibrium at 1100 °C is similar to that at 1000 °C. The Ni5Zr, Ni10Zr7, and Fe2Zr phases have solid solution composition ranges, but the Ni7Zr2, Ni21Zr8, NiZr, NiZr2, and Fe23Zr6 phases almost exhibit nearly linear compounds both at 1000 and 1100 °C. The solubilities of Fe in Ni7Zr2 phase and Ni in Fe2Zr phase are extremely large. At 1200 °C, the liquid phase of Zr-rich corner forms the continuous region from the Ni–Zr side to the Fe–Zr side. Additionally, the solubilities of Fe in Ni5Zr, NiZr phases and Ni in Fe23Zr6 phase clearly increase with increasing temperature to 1200 °C. The obtained results may provide a better understanding of microstructures and further development of the Ni–Fe–Zr alloys.

The Manganese dioxide/reduced graphene oxide (MnO2/RGO) double-shelled hollow microsphere with an improved electrical conductivity and accessible surface area has been synthesized using the monodispersive polystyrene (PS) microsphere as a self-sacrificing template. RGO/PS core–shell microsphere was prepared through π–π stacking interaction between PS microsphere and graphene oxide sheet, and then chemical reduction using hydrazine hydrate. MnO2/RGO/PS core-shell-shell microsphere was prepared through in situ chemical redox process between KMnO4 and benzyl alcohol-anchored RGO/PS. MnO2/RGO double-shelled hollow microsphere was obtained by etching PS microsphere from MnO2/RGO/PS using tetrahydrofuran. It had a pore diameter of 560–580 nm and layer thickness of 210–270 nm. Low charge transfer resistance of 0.3006 Ω and total electrochemical impedance of 2.37 Ω caused a high specific capacitance of 450.1 F g−1 at 0.2 A g−1. The capacitance retention of 81.7% after 1000 cycles indicated good cycling capability at 5 A g−1. MnO2/RGO double-shelled hollow microsphere presented the promising application for supercapacitor electrode material.

In the present study, Ti–6Al–4V alloy sheets having a thickness of 1.6 mm and 2 mm are chosen for carrying out weldability studies using gas tungsten arc welding (GTAW) process. The quality of the weld was examined through metallographic (macro- and micrographs) analyses. The welded specimens were subjected to mechanical tests to examine the behavior of tailor welded blanks (TWBs). Grain coarsening at fusion zone (FZ) and heat affected zone was confirmed through optical microscope. Transmission electron microscopy images showed the presence of thin α-phases surrounded by β-grains at FZ. The maximum hardness distribution of 383 HV is obtained at FZ. Tensile test results revealed an increase of 3.58% strength as compared to the thin base metal. At fracture surface, the presence of various sized dimples was identified through SEM. Erichsen cupping test showed that formability performance of the TWB was affected by a negligible percentage.

We analyze the effect of functionalization in the surface of zinc oxide crystal structure by 3-mercaptopropionic acid. X-ray powder diffraction data and extended x-ray absorption fine structure studies confirms a wurtzite structure. However, the morphology of the surface seems to be reduced and shows a film-like surface as demonstrated by x-ray absorption near edge structure and scanning electron microscopy. As a result of surface functionalization, the energy levels of the semiconductor were shifted toward reductive potentials (by 50 mV) as determined by diffuse reflectance and cyclic voltammetry.

We present two straightforward and cost-effective methods, based on metal-assisted chemical etching and a direct imprinting technique, to fabricate metal-covered porous amorphous silicon back reflectors for amorphous silicon solar cells. We demonstrate an increase of approximately 30% in both short-circuit current and overall efficiency with respect to a cell with a flat metal back reflector. This is achieved by implementing light trapping via either a roughened porous amorphous silicon layer or an imprinted periodic grating. This work provides a pathway to increase amorphous silicon solar cell efficiency via increased absorption without significantly impacting processing costs.

Al-based composites reinforced with Mg–7.4%Al mechanically alloyed particles have been synthesized by hot pressing followed by hot extrusion. Microstructural characterization of the bulk samples reveals the phase transformation of the reinforced particles (Mg(Al)ss + γ-Al12Mg17) to the stable intermetallic β-Al3Mg2 phase which occurs during consolidation. The phase transformation leads to the increase of effective volume faction of the reinforcement along with strong interfacial bonding, which causes a significant increase of the strength of the composites retaining appreciable plastic deformation. The strengthening can be attributed to the reduction of ligament size and to the interface strengthening due to better interface bonding (load-transfer) between the Al-matrix and the reinforcing particles.

The fracture behavior of a single-crystal Al-nanoplate with an edge crack under tensile loading was simulated using a molecular statics technique to evaluate crack growth resistance in Al. The crack length was determined using a stiffness method. A parabolic function fitted from simulation results was used to predict the crack length from the stiffness value extracted from unloading curves. Based on energy considerations, crack growth resistance was calculated. Crack growth resistance rose sharply in the initial stages of crack growth, and with an additional crack extension, it increased gradually to converge to a constant far exceeding the fracture toughness predicted by the Griffith criterion. This trend in the crack growth resistance curve was closely related to the amorphous zone formed at the crack tip after the onset of crack propagation.

The microstructures and mechanical properties of ternary (Ni75Al9V16) and multicomponent (Ni69Al9V9.5Nb3Ti1.5Co4Cr4) dual two-phase intermetallic alloys charged with C were investigated by scanning electron microscope, electron probe microscopic analyzer, x-ray diffraction, Vickers hardness, and tensile tests. Solid solubility limits of C in the dual two-phase microstructures were small, mostly less than 0.1 at.%. When C was charged exceeding the solid solubility limit, large-sized carbides were solidified with no structural coherency with the dual two-phase microstructure. Major transition metals constituting the carbides changed from Nb and Ti to V with increasing charged C content. This transition was correlated with the capability of the carbide formation. C dissolving in the dual two-phase microstructure enhanced hardness and flow strength through solid solution hardening without sacrificing tensile ductility. The formed carbides little contributed to strengthening, rather, contributed to softening through depleting constituent element V as well as alloying metals Nb, Ti, and Cr from the dual two-phase microstructures.

Dynamic loading of the hat-shaped specimen of 2195-T6 aluminum lithium alloy was carried out with a split Hopkinson pressure bar at ambient temperature. The formation and evolution mechanisms of adiabatic shear band (ASB) in this alloy were investigated and then microstructure was further observed. The microstructure within ASB in 2195 aluminum alloy was characterized by means of optical microscopy and transmission electron microscopy. The width of ASB was about 20–30 um. Nano-grains (50–100 nm) were observed in the middle of shear zone. Experimental results show that the diffusive transformation took place within ASB during high strain rate deformation, namely the precipitates dissolving in the matrix in the process (within about 71 µs). Based on thermodynamics and kinetics analyses, dissolution of precipitates was firstly investigated during adiabatic shearing deformation, and a dissolution model was suggested in the present work. The diffusive transformation and the microstructure evolution within ASB in 2195 alloy were explained.

Ni-doped ZnO hollow microspheres were fabricated by calcining the mixture of zinc and nickel citrate precursors at 500 °C for 2 h. The structure, composition, Barrett–Emmett–Teller specific surface area, and optical properties of Ni-doped ZnO samples were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, wave length dispersive x-ray fluorescence spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, N2 adsorption–desorption isotherms, and ultraviolet (UV)-visible diffuse reflectance spectroscopy. The photocatalytic results demonstrated that the as-synthesized Ni-doped ZnO microcrystals possessed much higher photocatalytic activity than pure ZnO in the decomposition of methylene blue under UV-light irradiation. The present work suggests that Ni-doped ZnO hollow microspheres can be applied as an efficient photocatalyst for water polluted by some chemically stable azo dyes.

A systematic analysis of effect of metallurgical defect and phase transition on geometric accuracy and wear resistance of iron-based parts fabricated by selective laser melting was conducted. By composition optimization of alloying elements, the desirable martensitic structure was directly obtained based on high-speed laser induction and the content of retained austenite was observed to be different under various laser parameters. Using an optimized scan speed of 1600 mm/s could lead to the highest densification level of 99.24% and the lowest content of retained austenite of 3.5%, hence acquiring a considerably high Rockwell hardness of 61.9 HRC, a reduced coefficient of friction of 0.40, and wear rate of 1.8 × 10−5 mm3/N m. A thorough investigation of dimension offset due to martensite transformation in conjunction with theoretical calculation was performed. Lower top surface roughness (5.25 μm) and reduced side roughness (13.84 μm) were achieved at the optimized scan speed of 1600 mm/s.