The effects of hydrogen-charging on tarnishing film-induced brittle cracking of brass were studied. The tarnishing film was generated on brass samples with various hydrogen concentrations in Mattsson’s solution, then removed from the solution, dried, and subjected to a slow loading rate (loading speed = 0.5 mm/min) in air. The results indicated that hydrogen caused the film-induced brittle cracking to be more difficult to occur and a considerably high concentration of hydrogen could inhibit completely the film-induced brittle cracking. Elastic modulus test results showed that elastic modulus of the brass substrate decreased and elastic modulus of the tarnishing film increased with increasing the hydrogen concentration. Hydrogen inhibiting the film-induced cracking can be ascribed to the fact that hydrogen changed the elastic modulus of substrate and film.

Ternary Sn-In-Cu alloys are prepared and equilibrated at 250 °C for 2 to 20 weeks. The phases formed in these alloys are experimentally determined. The 250 °C Sn-In-Cu isothermal section is established according to the phase equilibrium information obtained in this study and that of the three constituent binary systems. It has eight single-phase regions, namely liquid, δ1-Cu41Sn11, ε-Cu3Sn, δ2-Cu7In3, η-(Cu6Sn5, Cu2In), Cu11In9, Cu2In3Sn, and α-(Cu) phases, 14 two-phase regions, and seven three-phase regions. In the Sn-In-Cu system at 250 °C, the η-Cu6Sn5 and η-Cu2In phases form a continuous solid solution and the ternary Cu2In3Sn compound is observed. The δ1-Cu41Sn11 phase is stabilized at 250 °C with the introduction of indium although it transforms into α-(Cu) and ε-Cu3Sn phases via a eutectoid reaction around 350 °C in the binary Sn-Cu system. Except for the Cu11In9 phase and the Cu2In3Sn ternary compound, the other binary compounds all have significant indium and tin mutual solubilities.

Nanoindentation measurements of the grain interiors of an ultra-fine grained (UFG) pure Al produced by equal channel angular pressing were taken to evaluate the contribution of the matrix strength. Specimens were subjected to 0, 1, 2, 4, and 8 passes at ambient temperature. The nanohardness of the deformed samples was always higher than that of the undeformed sample 0P in the range of the indentation depth that was investigated, suggesting a strengthening of the matrix in the UFG Al. The increase in hardness that was contributed by the matrix to the macroscopic scale hardness was significantly large in about 40% of the deformed samples. The microstructural characterization and the deformation response analysis with the pop-in event during indentation suggested that the strengthening of the matrix originated from dislocation strengthening and some other presumable factors in the grain interiors.

The microstructure, lattice parameters, electrical conductivity, thermal expansion, and mechanical properties of (La0.8Ca0.2)(Cr0.9–xCo0.1Nix)O3–δ (x = 0.03, 0.06, 0.09, 0.12) were systematically investigated in this work. Nickel doping of (La0.8Ca0.2)(Cr0.9Co0.1)O3–δ is an effective way of increasing the thermal expansion coefficient (TEC) and stabilizing the high-temperature phase transformation from rhombohedral to tetragonal. As the nickel-doped content increases, the TEC increases parabolically by TEC (x) (ppm/°C) = 10.575 + 63.3x−240x2 (x = 0.03−0.12). The electrical conductivity of (La0.8Ca0.2)(Cr0.9–xCo0.1Nix)O3–δ specimens increases systematically with increasing nickel substitution in the range of 0.03 ≤ x ≤ 0.09 and reaches a maximum for the composition of (La0.8Ca0.2)(Cr0.81Co0.1Ni0.09)O3–δ (σ850 °C ∼60.36 S/cm). There is a slight increase in the fracture toughness with increasing nickel doping content, and the fracture toughness is strongly affected by the grain size. It seems that there is an increase in the fracture toughness with decreasing grain size. However, the microhardness does not significantly depend on the grain size in this study. The (La0.8Ca0.2)(Cr0.81Co0.1Ni0.09)O3–δ specimen shows high electrical conductivity, a moderate thermal expansion coefficient, and nearly linear thermal expansion behavior from room temperature to 800 °C. It will be suitable for interconnect materials for intermediate temperature solid oxide fuel cells (IT-SOFCs).

Effects of Fe incorporation into Al–Ti–B4C reactants on the combustion behaviors, reaction mechanism, synthesized products, and possible natural convection of fluids were investigated. The incorporation of Fe significantly promotes the self-propagating reaction and decreases the reaction dependence on the B4C particle size. The prior reaction of Fe with B4C leads to the decomposition of B4C and formation of Fe2B and free carbon. On the other hand, the reaction of Fe with Ti and Al gives rise to the emergence of Fe–Ti and Fe–Ti–Al eutectic liquids. As a result, the diffusivity and reactivity of the dissociated carbon and boron atoms are greatly facilitated and the reaction is substantially promoted, yielding a desirable product of TiC, TiB2, and FeAl phases. Moreover, the incorporation of Fe may enhance free convection of the molten phase in the reaction zone and thus contribute to the combustion synthesis process.

Ambient temperature α-to-β phase transition and nanocrystallization in the aged Ti–25Nb–3Mo–3Zr–2Sn titanium alloy was achieved by surface mechanical attrition treatment (SMAT). The phase transition occurs at α/β interfaces and extends to α phase interiors with increasing strain. It is irreversible and diffusion controlled. The stress-induced increase of Gibbs energy and enrichment of Nb may cause a high order of lattice instability of the α phase adjacent to the α/β interfaces and compel the α phase to β phase. The presence of fine α needles in the aged alloy and the phase transition from α to β with increasing strain are viewed to play a crucial role in the subsequent nanostructuring.

An Sn-patch formed in Ni(V)-based under bump metallization during reflow and aging. To elucidate the evolution of the Sn-patch, the detailed compositions and microstructure in Sn–Ag–Cu and Ti/Ni(V)/Cu joints were analyzed by a field emission electron probe microanalyzer (EPMA) and transmission electron microscope (TEM), respectively. There existed a concentration redistribution in the Sn-patch, and its microstructure also varied with aging. The Sn-patch consisted of crystalline Ni and an amorphous Sn-rich phase after reflow, whereas V2Sn3 formed with amorphous an Sn-rich phase during aging. A possible formation mechanism of the Sn-patch was proposed.

The effects of soft impingement on precipitation are considered. A physically realistic analytical treatment of soft impingement has been developed for solid-state precipitation in a nonisothermal heating/cooling process following the basic assumptions (i.e., a two-stage transformation including site saturation of nucleation, isotropic growth and linear approximation for a concentration gradient in front of the precipitate/matrix interface). Furthermore, both one- and three-dimensional precipitations have been described using a compact expression which is analogous to Zener’s model but with a temperature-dependent growth coefficient. A detailed description for the model parameters has been given for the model application. Good agreement with published experimental data, for example, the decomposition of austenite in a 0.038–0.30wt%Mn plain carbon steel, has been achieved.

A high quantity of tungsten oxide nanosheets were synthesized by oxidizing tungsten plates with potassium hydrate as the catalyst and tungsten plate as the substrate. The structural and geometrical properties were characterized by various techniques. It was found that the crystalline nanosheets have a WO3 structure with thicknesses of 30–50 nm and widths up to tens of micrometers. There exist two characteristic acute angles of about 37° or 51° on the nanosheet plane. The formation of these angles and the growth mechanism were discussed.

As potential substitutes for traditional Ti(Zr)–Cu–Ni-based brazing metals for high strength Ti alloys as well as a study for metallic glass, Zr–Ti–Ni-based alloys have been attracting much attention recently. In this study, the melting temperatures and microstructures of the Zr(Ti)-rich Zr–Ti–Ni alloys with Ni content below 33.3 at.% were systematically studied. A ternary deep eutectic alloy consisting of three phases was found at the composition of Zr50Ti26Ni24 with a solidus temperature of 798 °C and a liquidus temperature of 809 °C, which are significantly lower than the Zr2Ni–(Zr,Ti)2Ni pseudobinary eutectic melting temperature of 850 °C. This ternary eutectic reaction can be presented as L → α-(Zr/Ti) solid solution + Zr2Ni + ternary Laves (Zr,Ti)2Ni.

We investigated the effects of gamma irradiation doses of 50, 100, and 103 kGy on boron-doped diamond (BDD) thin films synthesized using microwave plasma-assisted chemical vapor deposition with varying boron concentrations of [B]/[C]gas = 100, 1000, 2000, and 4000 ppm. The diamond thin films were characterized prior to and post-irradiation and the influence was assessed in terms of morphology, structure, and physical properties using scanning electron microscopy, atomic force microscopy, x-ray diffraction, vibrational spectroscopy (Raman and IR), x-ray photoelectron spectroscopy, and electrical measurement techniques. The results clearly showed that the response of gamma irradiation on BDD films was distinctive compared to those of undoped diamond films with changes in electronic behavior from metallic (>1019 to 1020 cm–3) to semiconducting (≤1019 cm–3), especially in the case of heavily boron-doped diamond films demonstrated by micro-Raman spectroscopy and electrical property characteristics. In fact, this modification in electrical property behavior induced by “gamma conditioning” can be effectively used to fine control boron doping in chemically vapor deposited diamond much needed for various electronic devices. The “gamma conditioning” refers to material processing by radiation which helps to passivate electrically active boron and defects with hydrogen migration thus fine tunes the boron acceptor concentration albeit that this is difficult to achieve during BDD film deposition. In addition, the results also indicate that almost all of the BDD films studied hereby tend to reach a state of damage saturation when submitted to gamma irradiation of 103 kGy. We discuss our novel findings in terms of the interplay of boron-hydrogen in diamond with possible multiple scenarios: (i) the generation of point/Frenkel defects due to Compton scattered electrons, (ii) the formation of a nonmetallic boron-rich borocarbide (e.g., B13C2) phase, (iii) the passivation of electrically active acceptor (B) sites due to the invariable presence of H in the grains and at the grain boundaries, (iv) the desorption of H from the diamond surface, and (v) the “priming or pumping” effect, which improves the electronic properties by compensating for the shallow boron acceptors to produce semiconducting/insulating material, verified by the cold neutron depth profiling technique.

The initiation and evolution of shear bands in Zr64.13Cu15.75Ni10.12Al10 bulk metallic glass tensile samples has been investigated in situ by scanning electron microscopy. The initial shear band originates from the highest stressed area, and does not propagate during further tension, which is attributed to the weakening of the stress field in front of the shear band tip, possibly caused by atomic rearrangement and local temperature rise. As a result, multiple shear bands occur in sequence with gradually increased length and offset. This result is due to the fact that the stress in front of the tip of the initial shear band does not concentrate again during further tension above the shear yield strength. Numerical analysis was carried out to investigate the stress distribution under tension, suggesting that the maximum pressure-dependent shear stress criterion overestimates the yield strength, while the shear plane criterion describes the conditions for the formation of shear bands well.

Monodisperse spherical Y2O2S:Yb,Ho nanocrystals with particle size about 50 nm were prepared by a modified homogeneous precipitation method combined with low-temperature sulfurization process. The Y2O2S:Yb,Ho nanocrystals exhibit an intense green emission assigned to the Ho3+ ions 5F4, 5S2 → 4I15/2 transition under 980 nm infrared pump. The upconversion luminescence brightness of Y2O2S:Yb,Ho is 526 Cd/m2 under 4.63 W/cm2 pump density, indicating that the as-prepared Y2O2S:Yb,Ho nanocrystals can meet the requirement of in vivo imaging. The formation mechanism of monodisperse spherical oxysulfide nanoparticles is also discussed.

A simple empirical method that extracts the elastic moduli of both thin films and the underlying substrates is proposed and validated by both new nanoindentation experiments and published data. Deconvolution of thin film’s elastic properties from the substrate is achieved by statistical estimation, where a simple function relating the elastic moduli of the thin film and substrate to the film-substrate composite modulus is used to fit the experimental data plotted against the logarithmic indentation depth normalized by film thickness. Experimental data from a wide range of soft and hard films on substrate were used to demonstrate the deconvolution and validate the method. The estimated elastic moduli of thin films and substrates agree well with their corresponding standard values or values obtained by other methods. The advantages of this method are discussed, and recommendations are made on how to design experiments to obtain reliable data for this method.

The refinement mechanism of pulsed magnetic field (PMF) was discussed by experimental investigation, and the effects of exciting frequency, exciting voltage, and delay time of PMF on grains refinement of superalloy were studied. The experimental results show that, as exciting frequency or exciting voltage is increased, the grains are refined. However, the grains become coarse when frequency increases further. As delay time of PMF increases, the grain size increases. The refinement effect of PMF is attributed to the detachment of heterogeneous nuclei on the mold wall and subsequently separation of nuclei in the melt. The Joule heat can prolong the continuous nucleation process. However, the refinement effect will be impaired if the Joule heat is strong enough to remelt the detached nuclei.

The influence of prior cold deformation on precipitating of alpha phase as well as the variation of hardness during aging has been investigated in solution-treated Ti-10Mo-8V-1Fe-3.5Al alloys. The results show that alpha phase precipitation could be obviously accelerated by the prior cold deformation. In the predeformed samples, a network pattern structure was observed with an optical microscope after aging treatment. It could be attributed to the phenomenon that the plate-shape alpha precipitates prefer to nucleate and grow in the regions with a high density of dislocations, especially inside slip bands. The hardness of both the predeformed and undeformed TB3 specimens after different aging times was measured and further predicted by a proposed strengthening model based on the grain refinement mechanism of the beta phase. The predicted results are consistent with the experimental results, especially in the later aging stages.

A series of molecular dynamics simulations was performed to study grain boundary sliding of three types of [101¯0] tilt grain boundaries in a magnesium bicrystal. In particular, a near Σ11 twin boundary, an asymmetric near Σ11 twin boundary, and a θ = 40.3° general [101¯0] tilt grain boundary were studied. Simulations showed that grain boundary sliding (a rigid motion of two grains relative to each other along boundary plane) did not occur over the stress range applied; instead, coupled shear motion (grain boundary sliding induced boundary migration) was dominant. Although the measured coupling coefficient, the ratio of boundary tangential displacement to boundary normal displacement, was in good agreement with theoretical prediction, the detailed shear behavior was different, depending on types of grain boundary, magnitude of applied shear stress, and temperature. It was also noted that grain boundary twining was the predominant mechanism that allowed the coupled shear motion to occur in hexagonal close-packed (HCP) magnesium.

Multichannel acoustic emission (AE) measurements by four laser interferometers were developed and applied during a plasma-spray coating process that is known as being a high-temperature process and an extremely noisy environment in both mechanical and electrical domains. The AE signals could be successfully detected during the cooling period after the deposition, and it was clearly indicated that a higher preheating temperature resulted in the improvement of bonding between splats and/or at the interface of the coating and the substrate. The maximum principal stress generated during the deposition process was calculated by the transient heat and stress analysis and the obtained AE events. The critical stress for crack initiation of the alumina coating on a steel substrate with an NiCr bond coat layer was estimated as 30∼45 MPa. The developed techniques were shown to be a potential tool for in situ monitoring of the thermal spray process, by which an increase in the reliability of thermal spray coatings can be expected.

This investigation analyzed the effect of reactant particle size on the stress development characteristics of NiAl synthesized through self-propagating high temperature synthesis. Four sample combinations of NiAl were synthesized based on initial particle diameters of the reactants: (i) 10 μm Al and 10 μm Ni (S1), (ii) 10 μm Al and 100 nm Ni (S2), (iii) 50 nm Al and 10 μm Ni (S3), and (iv) 50 nm Al and 100 nm Ni (S4). Characterization of NiAl was performed by parallel comparison of the distribution of residual stresses of the samples prior to and after the reaction. Residual stresses were quantified using x-ray diffraction. Upon characterization it was found that combinations S1, S2, and S3 exhibited tensile residual stresses, while combination S4 exhibited compressive residual stresses. Statistical analysis confirmed that self-propagating high temperature synthesis products derived from nanoparticle reactant sizes exhibited compressive residual stresses offering improved fatigue resistance in composite production.

Using a cold graphite mold casting method, bulk AlNiY chill-zone alloys were prepared at hypereutectic compositions with Al content from 85 at.% to 94 at.%. It was found that ultra-hard surface layers with a thickness of about 200 μm and submicron grain size form when the melt can be undercooled without heterogeneous nucleation at the mold contact surface. This hard chill-zone forming in contact with the mold possesses Vickers microhardness Hv about 350–420 and is thus harder than fully amorphous Al alloys. In compression, ultimate strength more than 1.1 GPa and true strain more than 150% without failure were achieved simultaneously. The combination of high strength and good plasticity will be discussed in relation to the special structure of the chill-zone alloy.