Fracture toughness and its deformed structures were investigated on a Mg–3Al–1Zn (AZ31) alloy processed by direct extrusion. The average grain sizes of the alloy after extrusion at temperatures of 473 and 573 K were 4.0 and 14.5 μm, respectively (i.e., fine-grained and coarse-grained alloys). The plane-strain fracture toughness, KIC, as determined by stretched zone analysis in fine-grained and coarse-grained alloys was estimated to be 24.9 and 22.7 MPam1/2, respectively. Microstructural observations of the fine-grained alloy after fracture toughness testing showed that non-basal slip and grain-boundary sliding was activated even at room temperature. In addition, the {10-12} deformation twins were observed despite the fine-grained structures. However, the fraction of deformation twins was reduced with grain refinement, which related to the enhancement of fracture toughness with grain refinement.

A new quaternary layered carbide, (ZrC)3[Al3.56Si0.44]C3, has been synthesized and characterized by x-ray powder diffraction and thermopower and electrical conductivity measurements. The crystal structure was successfully determined using direct methods and further refined by the Rietveld method. The crystal is trigonal (space group R3m*, Z = 3) with lattice dimensions a = 0.331389(7), c = 4.90084(7) nm, and V = 0.46610(1) nm3. The final reliability indices calculated from the Rietveld refinement were Rwp = 9.53% (S = 1.70), Rp = 7.22%, RB = 1.81%, and RF = 0.94%. The crystal structure is composed of the NaCl-type [Zr3C4] slabs separated by the Al4C3-type [Al0.89Si0.11C] layers. This material had thermoelectric properties comparable to the layered carbides (ZrC)2[Al3.56Si0.44]C3 (Zr2[Al3.56Si0.44]C5), (ZrC)2Al3C2, and (ZrC)3Al3C2 in the temperature range of 373–1273 K, with the maximal power-factor value of 6.6 × 10−5 W m−1K−2 at 545 K. The two quaternary carbides have been found to form a homologous series with the general formula of (ZrC)n[Al3.56Si0.44]C3 (n = 2 and 3).

A method is described for the quantification of BaCeO3 formation during the growth of YBa2Cu3O7–x (YBCO) films on CeO2 buffer layers. The method is based on the selective etching of BaCeO3 followed by inductively coupled plasma (ICP) excitation spectroscopy. A 10% HNO3 solution, at room temperature, dissolved BaCeO3 and YBCO in minutes but did not significantly etch CeO2 films. ICP excitation spectroscopy was used to quantify the extent of the reaction over macroscopic areas of film (∼1 cm2). BaCeO3 peak areas were measured by x-ray diffraction (XRD) and calibrated to the ICP excitation spectroscopy results. XRD and ICP excitation spectroscopy results indicated that BaCeO3 formation through a metalorganic deposition (MOD)-derived CeO2 layer follows the parabolic growth law. Almost the entire ceria cap layer was consumed by the growth of BaCeO3 after 2 h at 760 °C in the MOD process examined. BaCeO3 growth was substantially slower at 725 °C; only 25 ± 3% of the ceria layer reacted.

The role of MgAl2O4 spinel particle dispersion for attaining high-strain-rate superplasticity (HSRS) was examined in tetragonal ZrO2. Microstructural examination shows that the dispersed spinel particles provide the following positive factors to ZrO2 simultaneously: (i) stable fine grain size by retarding grain growth due to pinning effect; and (ii) enhanced accommodation due to accelerated lattice diffusivity caused by the dissolution of aluminum and magnesium into ZrO2 from the spinel particles, and accelerated relaxation of stress concentrations exerted by grain boundary sliding through dislocation motion. These positive factors make it possible to attain HSRS in ZrO2.

This study shows that biaxially textured SmxZr1−xOy (SZO) with a wide range of compositions (0.06 < x < 0.75) can be grown directly on ion-beam-assisted deposition (IBAD) MgO template using reactive cosputtering. The SZO crystal structure can be changed, and the lattice parameter can be tailored (from 5.23 to 5.49 Å) by changing the composition. We have developed a simplified high-temperature superconducting coated conductor using SZO as the buffer layer. YBa2Cu3O7−δ (YBCO) films grown by pulsed laser deposition on the SZO buffered IBAD MgO have self-field critical current densities (Jc) in the 2–4 MA/cm2 range. The in-field measurements demonstrate that high-quality YBCO films can be grown on SZO buffered IBAD MgO. The present results are especially important because they were obtained on coated conductors with the simpler architecture by eliminating the additional homoepitaxial layer of MgO. This translates in faster production and lower manufacturing cost.

The variation of a Zr57Nb5Cu15Ni13Al10 bulk metallic glass’s elastic constants with temperature and thermal history was investigated, using an impulse excitation technique for resonant vibration analysis. The Young’s modulus at 550 K is 78 GPa with a slope of −17 MPa/K in the glass as-produced and increases to 80 GPa with a slope of −26 MPa/K upon annealing. The modulus of the supercooled liquid at 700 K is 74 GPa with a slope of −90 MPa/K, whereas for the crystallized material E = 100 GPa with a slope of −15 MPa/K. These results are interpreted in terms of the vibrational and configurational contributions to the temperature dependence and compared with calorimetry data.

Monolithic TiN and multilayered structures of TiN films that alternate with thin Ti interlayers were coated by filtered arc deposition onto a stainless steel substrate. Microscratch tests with a diamond indenter of 5-μm radius were carried out in combination with focused ion beam (FIB) sectioning and scanning and transmission electron microscopy to explore the controlling deformation mechanisms of these TiN coatings in relation to their microstructural design. It was found that for the monolithic TiN coating, columnar TiN grains slid against each other under normal forces and, at the same time, tilted under tangential forces. For the TiN multilayers, however, intercolumnar shear sliding was suppressed considerably by the multilayered structure and the interlayers, and grain tilting occurred largely within the upper TiN layer, presumably due to the shear effect of the soft Ti interlayers. With further increases in tangential force, rupture of TiN grains was observed within both types of coatings; for the TiN multilayers, rupture of TiN grains occurred predominantly within the layers close to the steel substrates. It can be concluded that the application of TiN multilayers provides better resistance to contact damage than the traditional monolithic TiN coatings did.

The aim of the present work was to study the morphological, structural, and chemical analysis as a function of depth in vanadium alloys with a 5 at.% of titanium implanted at 673 K with 1.2 keV N+ ions, by transmission electron microscopy (TEM), glow discharge (GD) analysis, and x-ray photoemission spectroscopy. These results are correlated with those of previously published nanoindentation tests, and the species and chemical states responsible for the increase in hardness are identified. The maximum increase in hardness corresponds to the highest N concentration, measured by both photoemission spectroscopy and GD. In addition, the thickness of the layer (≈1000 nm), where structural modifications are observed using TEM, can also be directly correlated with the thickness of the implanted layer, where an incremental increase in hardness has previously been measured. These findings support the conclusion that the formation of vanadium and titanium nitride/oxynitrides (–N–O,–O–N–H) compounds are responsible for the increased hardness of these V–5at.% Ti samples implanted with N at low ion energy and high sample temperature.

Multiaxial deformation of Zr55Al10Ni5Cu30 metallic glass was investigated by instrumented indentation tests with a spherical indenter. Contrary to the elastic–rigid-plastic behavior of bulk metallic glasses (BMGs), indentation pressure showed a significant increase with increasing indentation strain, and it was ascribed to a rapid transition of the plastic constraint factor (PCF). However, it was impossible to measure the PCF values from the indentation pressures in the Zr-based BMG because information on uniaxial flow stress was insufficient due to the limited flow strain of 2.2%. Here we developed a PCF assessment method using a relative residual depth hf/hmax, which was experimentally confirmed by adopting it to spherical indentations of a steel sample having well-known flow properties. Flow properties of the BMG were calculated using the new PCF assessment method, and the effects of the materials pileup and low strain indentations on PCF and flow properties were discussed.

“Extracting the elastic and viscoelastic properties of a polymeric film using a sharp indentation relaxation test” [J. Mater. Res. 21, 2991 (2006)]

An experimental study of the elastic and plastic properties of sucrose single crystals, which can be considered to be a model material for both pharmaceutical excipients and explosives, has been carried out using nanoindentation. Instrumented indentation was used to characterize the properties of both habit and cleavage planes on the (100) and (001) orientations; the elastic modulus on the (100) is 38 GPa, while the modulus on the (001) is 33 GPa. The hardness of sucrose is approximately 1.5 GPa. Nanoindentation enables assessment of the onset of plastic deformation on cleaved surfaces, and a maximum shear stress of 1 GPa can be supported prior to plastic deformation. The deformation in this material is crystallographically dependent, with pileup around residual indentation impressions showing evidence of preferential slip system activity.

The kinetics of second phase formation during the thermal annealing of crystalline and amorphous LiNbO3(LN) thin films was investigated. When c-axis-oriented LN texture film was annealed at temperatures higher than 700 °C, Li2O desorbed from the surface and grain boundaries, which induced epitaxial precipitation of the LiNb3O8phase on the LN (0001) plane. While the LiNb3O8volume exhibited saturation behavior against annealing time, oxygen atoms continued to diffuse out from the inner part of the film. Arrhenius plots of the rate of LiNb3O8formation and oxygen loss were scaled with common activation energy of 30.5 kcal/mol. In terms of phase formation from amorphous LN, annealing at 700 °C in a vacuum induced rapid crystallization into mixtures of LN and LiNb3O8, the volume ratio of which can be explained by the phase separation model. Annealing in an O2atmosphere, however, produced an incubation time before crystallization and a larger volume fraction of LiNb3O8after crystallization. Oxygen molecules that penetrated into the film will hinder the migration of atoms and decelerate crystallization. Vacancies produced as a result of Li2O loss will facilitate the nucleation of LN and LiNb3O8pairs while maintaining the epitaxial relation.

Simultaneous direct current stressing with thermal aging accelerates the migration of conducting species resulting in significant microstructural coarsening. Because of the synergistic fields influence, such coarsening begins from the anode and propagates toward the cathode. Prolonged current stressing with 104 A/cm2 at 150 °C causes the inter-lamellar eutectic SnPb to become a two-layer structure, with a Pb-rich layer adjacent to the anode and an Sn-rich layer adjacent to the cathode. This mass movement causes hillock/valley formation, and the extents of such surface undulations increase with increases in the time duration of current stressing as well as with the joint thickness. In thinner solder joints these events occur sooner, although the extents of surface undulations depend on the thickness of joints. In addition, Cu present in the substrate and in the intermetallic layer at the cathode migrates to form Cu6Sn5 within the Sn-rich layer, in a region close to the Pb-rich layer.

A highly crystallized and smooth-surfaced zirconia (ZrO2) thin film was prepared using a precursor solution with 2,4-pentanedione addition (molar ratio of 1:1 for zirconium alkoxide); the film was irradiated with ultraviolet (UV) light using an ultrahigh-pressure mercury lamp. This thin film was compared with another thin film, which prepared using a precursor solution without additives and UV irradiation. The crystallinity of ZrO2 thin films improved with increasing 2,4-pentanedione addition and UV irradiation time and changed according to the type of organic additives. These results occurred presumably because the orientation of polymerization in zirconium alkoxide units and stability of chelate compounds for UV irradiation were controlled under these conditions. In addition, the method was effective for lower-temperature crystallization of highly crystallized, smooth-surfaced thin films.

An all-alkoxide sol-gel route to the formation of Nd1/3La1/3Ca1/3MnO3thin films and powders has been developed. The microstructural evolution on heat treatment of the gel to yield the perovskite oxide was monitored by means of thermogravimetric analysis-differential scanning calorimetry, powder x-ray diffraction (XRD), Fourier transform infrared spectroscopy, and transmission electron microscopy (TEM)-energy dispersive spectroscopy (EDS). It was found that the amorphous gel consists of hydrated oxo-carbonate without organic residues, and on heating it decomposes in several steps, finally forming single-phase perovskite at 680 °C. Further heating results in only slight changes in the cell parameters and crystal growth. Films were prepared by spin coating, followed by heat treatment in air to a temperature of 800 °C, and studied by scanning electron microscopy, TEM-EDS, and XRD. Films on Al2O3were more porous, while films on Pt–TiO2–SiO2–Si were rather dense and consisted of areas with different crystal orientations.

The paper correlates the growth and structure formation with the properties of indium-tin-oxide (ITO) films fabricated by pulsed reactive magnetron deposition onto amorphous substrates held at elevated temperatures ranging from room temperature to 510 °C. The evolution of the microstructure is consistent with the well-known structure zone model. The temperature dependence of the film texture is described with consideration of the interplay between the shadowing and surface-diffusion processes. It is shown that deposition at elevated temperatures lowers the crystallization threshold and is more effective in reducing resistivity than the postdeposition vacuum annealing at comparable temperatures. The films grown at a substrate temperature of 400 and 510 °C have the lowest resistivity of 1.2 × 10−4 Ω cm, the highest free electron density of 1.2 to 1.0 × 1021 cm−3, and mobility of 35–42 cm2 V−1 s−1 and exhibit the strongest (222) texture with the largest grain size.

The pseudo-binary (quasi-equilibrium) phase diagram for Zr-based bulk metallic glasses with crystalline in situ precipitates (β phase) has been constructed from high-temperature phase information and chemical composition analysis. The phase evolution was detected in situ by high-energy synchrotron x-ray diffraction followed by Rietveld analysis of the data for volume fraction estimation. The phase diagram delineates phase fields and allows the control of phase fractions. Combined with related previous work by the authors, this diagram offers a unique opportunity to control both the morphology and volume of the dendritic β phase precipitates to enhance the properties of the composites.

A new bulge testing setup for the measurement of the mechanical properties of thin films is presented. This self-built device can be incorporated in an atomic force microscope (AFM), which allows the recording of topographic images of the observed sample membranes under load conditions. Bulge test experiments on different silicon nitride films are presented and compared to nanoindentation experiments. The measured elastic moduli from nanoindentation and bulge testing are in good agreement. Apart from that, the ability to extract stress–strain data from AFM scans is shown, and the results are compared to standard bulge testing experiments. Imaging of the sample microstructure under load conditions is demonstrated on a thin Cu film.

Recently published results for a rigid spherical indenter contacting a thin, linear elastic coating on a rigid planar substrate have been extended to include the case of two contacting spheres, where each sphere is rigid and coated with a thin, linear elastic material. This is done by using an appropriately chosen effective radius and coating modulus. The earlier work has also been extended to provide analytical results that span the transition between the previously derived Derjaguin–Müller–Toporov (DMT)-like (work of adhesion/coating-modulus ratio is small) and Johnson–Kendall–Roberts (JKR)-like (work of adhesion/coating-modulus ratio is large) limits.

Thick and crack-free Pb(Zr,Ti)O3 [PZT] films were fabricated on platinized silicon substrates by a multisputtering technique. The PZT films were deposited on the Si substrate by the radio frequency magnetron sputtering method using a single oxide target. As the film became thicker, its grain size increased. Therefore, the microstructure of the film was able to be controlled by repeatedly depositing thin layers. In addition, by using a seed layer with the same composition but a much smaller grain size, it was possible to further reduce the grain size of the film. When the film had a small in-plane grain size and a fibrous columnar structure, it was highly resistant to cracking, presumably because of its enhanced strength and structural stability. By exploiting these phenomena, highly dense, crack-free, and thick PZT films were successfully deposited up to a thickness of about 5 μm. The evolution of the crystallographic orientation of the film as a function of its thickness was also observed and correlated with the total strain energy of the system.