In situ devitrification and consolidation of gas atomized Al87Ni8La5 glassy powders into highly dense bulk specimens was carried out by spark plasma sintering. Room temperature compression tests of the consolidated bulk material reveal remarkable mechanical properties, namely, high compression strength of 930 MPa combined with plastic strain exceeding 25%. These findings demonstrate that the combined devitrification and consolidation of glassy precursors by spark plasma sintering is a suitable method for the production of Al-based materials characterized by high strength and considerable plastic deformation.

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 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.

The wettability of Pb-free Sn-based solder over the Cu-based Cu60Zr30Ti10 bulk metallic glass surface was investigated. We observed that the as-polished surface was nonwetting for the solder, which was due to the surface oxide layer of ZrOx formed in air. After complete removal of the oxide layer, a thin layer of Ag was deposited on the clean Cu60Zr30Ti10 surface. The Ag-covered Cu60Zr30Ti10 surface showed relatively high resistivity to the reoxidation even in air, and thus the wettability of the Cu60Zr30Ti10 surface for the Sn-based solder was greatly improved.

New Cu-based bulk glassy alloys (BGAs) with high glass-forming ability (GFA) were synthesized in a Cu-Zr-Al-Ag system. As the compositions of Cu-Zr-Al-Ag alloys with lower Ag and Al content shifted to the Cu-rich range, the supercooled liquid region, reduced glass transition temperature, and γ value increased, leading to the improvement of GFA. The best GFA is located around Cu47Zr45Al5Ag3, which is close to eutectic. Fully glassy samples with diameters up to 15 mm were fabricated by copper mold casting. These Cu-based BGAs exhibit excellent mechanical properties under compression. A large Young's modulus of 104–111 GPa, high fracture strength of 1905–1942 MPa, and distinct plastic strain of 0.002–0.011 were obtained. Additionally, the BGAs also show good corrosion resistance in 1 N H2SO4 solution.

A Cu- and Ni-free Zr-based metallic glass with high glass-forming ability was found in the Zr-Al-Co ternary system. The eutectic Zr56Al16Co28 alloy could be cast into glassy cylindrical rods with diameters up to 18 mm. The glassy alloy exhibited high tensile fracture strength of 1830 MPa and low Young's modulus of 83 GPa in conjunction with better corrosion resistance compared with the glassy Zr57Nb5Al10Ni12.6Cu15.4 in a simulated body fluid. Hydrothermal-electrochemical treatment in the aqueous 5M-NaOH solution resulted in the formation of amorphous sodium cobaltate layer on the surface of glassy Zr56Al16Co28 alloy. Hydroxyapatite was spontaneously formed on the surface of the alloy, indicating bioactivity after surface modification. The discovery of a Cu- and Ni-free Zr-based metallic glass with a critical diameter larger than 1 cm in conjunction with excellent mechanical properties, superior corrosion resistance, and good bioactivity may open up the application field as biomaterials.

The coarsening of polyhedral grains in a liquid matrix was calculated using crystal growth and dissolution equations used in crystal growth theories for faceted crystals. The coarsening behavior was principally governed by the relative value of the maximum driving force for growth (Δgmax), which is determined by the average size and size distribution, to the critical driving force for appreciable growth (Δgc). When Δgmax was much larger than Δgc, pseudonormal grain coarsening occurred. With a reduction of Δgmax relative to Δgc, abnormal grain coarsening (AGC, when Δgmax ≥ Δgc) and stagnant grain coarsening (SGC, when Δgmax < Δgc) were predicted. The observed cyclic AGC and incubation for AGC in real systems with faceted grains were explained in terms of the relative value between Δgmax and Δgc. The effects of various processing and physical parameters, such as the initial grain size and distribution, the liquid volume fraction, step free energy, and temperature, were also evaluated. The calculated results were in good agreement with previous experimental observations.

Correlated force and contact resonance versus displacement responses have been resolved using load-dependent contact-resonance atomic force microscopy (AFM) to determine the elastic modulus of low-k dielectric thin films. The measurements consisted of recording simultaneously both the deflection and resonance frequency shift of an AFM cantilever probe as the probe was gradually brought in and out of contact. As the applied forces were restricted to the range of adhesive forces, low-k dielectric films of elastic modulus varying from GPa to hundreds of GPa were measurable in this investigation. Over this elastic modulus range, the reliability of load-dependent contact-resonance AFM measurements was confirmed by comparing these results with those from picosecond laser acoustic measurements.

We introduce a novel method to correct for imperfect indenter geometry and frame compliance in instrumented indentation testing with a spherical indenter. Effective radii were measured directly from residual indentation marks at various contact depths (ratio of contact depth to indenter radius between 0.1 and 0.9) and were determined as a function of contact depth. Frame compliance was found to depend on contact depth especially at small indentation depths, which is successfully explained using the concept of an extended frame boundary. Improved representative stress-strain values as well as hardness and elastic modulus were obtained over the entire contact depth.

A new method is proposed to determine the elastic modulus and residual stress of freestanding thin films based on nanoindentation techniques. The experimentally measured stiffness-displacement response is applied to a simple membrane model that assumes the film deformation is dominated by stretching as opposed to bending. Dimensional analysis is used to identify appropriate limitations of the proposed model. Experimental verification of the method is demonstrated for Al/0.5 wt% Cu films nominally 22 µm wide, 0.55 µm thick, and 150, 300, and 500 µm long. The estimated modulus for the four freestanding films match the value measured by electrostatic techniques to within 2%, and the residual stress to within 19.1%. The difference in residual stress can be completely accounted for by thermal expansion and a modest change in temperature of 3 °C. Numerous experimental pitfalls are identified and discussed. Collectively, these data and the technique used to generate them should help future investigators make more accurate and precise measurements of the mechanical properties of freestanding thin films using nanoindentation.

We report that various metallic glassy nanostructures including nanoridges, nanocones, nanowires, nanospheres, and nanoscale-striped patterns are spontaneously formed on the fracture surface of bulk metallic glasses at room temperature. A clear correlation between the dimensions of these nanostructures and the size of the plastic zone at the crack tip has been found, providing a way to control nanostructure sizes by controlling the plastic zone size intrinsically or extrinsically. This approach to forming metallic glassy nanostructures also has implications for understanding the deformation and fracture mechanisms of metallic glasses.

Antiferroelectric (AFE) Pb0.92La0.08Zr0.95Ti0.05O3 (PLZT) films were grown on nickel foils with lanthanum nickel oxide buffer by chemical solution deposition. We observed field-induced AFE-to-ferroelectric (FE) phase transition. The electric field for the AFE-to-FE phase transition (EAF ≈ 270 kV/cm) and that for the reverse phase transition (EFA ≈ 230 kV/cm) were measured at room temperature on samples with PLZT films of ≈1-µm thickness. Relative permittivity of ≈560 and dielectric loss of <0.05 were measured near zero DC bias field. Hysteresis loop analysis showed that energy densities of ≈53 and 37 J/cm3 can be stored and recovered from the film-on-foil capacitors at 25 and 150 °C, respectively. Highly accelerated life tests were conducted. The projected mean time to failure is >5000 h when the capacitors are operated at room temperature with an applied field of ≈300 kV/cm.

Carbon nanofibers (CNFs) with different microstructures were synthesized by thermal chemical vapor deposition using different growth temperatures and methane/nitrogen gas mixtures. High-resolution transmission electron microscopy images revealed that bamboolike structure could be formed both by increasing the growth temperature and by increasing the nitrogen content in the reaction atmosphere at a lower growth temperature. Elemental analysis results indicated that no significant change in the nitrogen concentration was found regardless of the increase of nitrogen flow in the feed gas. The formation of bamboolike structure of CNFs and the effect of nitrogen gas on the microstructure change of CNFs were discussed.

The ignition and reaction processes of the thermal explosion reaction from the Ti–B4C system in air were studied. The thermal explosion reaction for the formation of TiC and TiB2 can be initiated at a relatively low temperature with the incorporation of air. Generally, the ignition process in air is suggested to be a chemical oven rather than gas transport, and the reaction process is proposed to be dissolution and precipitation.