The microstructures and chemical composition of nano-precipitates in vanadium (V) steels were investigated by the alloy contrast variation method (ACV) using small-angle X-ray scattering (SAXS) coupled with small-angle neutron scattering (SANS) at holding temperatures ranging between 600 and 700°C. Both the SAXS and SANS profiles exhibited clear scattering, depending on the holding temperature, due to the presence of nano-precipitates. The scattering profiles of the precipitates are characteristic of spherical or disc-like particles. The average diameters of these precipitates increased from 0.5 nm at 600°C to 23 nm at 700°C, whereas the number density of the precipitates decreases with increased holding temperature. Therefore, the increasing holding temperature results in an increase in the growth rate of the precipitates. ACV analysis revealed that the chemical composition of the precipitates corresponds to NaCl-type vanadium carbide (VC) at 675 and 700°C, and as VC0.9 at 625 and 650°C. The formation of a different heterogeneity, non-NaCl type, was found in the sample at a holding temperature of 600°C. This probably corresponds to a precursor of the NaCl phase in the initial process of precipitation.

We report on X-ray reflectivity of ultrathin polystyrene films with thickness h, which is comparable to the radius of gyration R g . Tiny jumps in thickness, accompanying an increase in surface roughness and decrease in electron density, are reproductively observed at around 80 C and 92 C only with increasing temperature. For films thinner than R g , the jump at 92 C disappears. However, films of 2R g thick, the jump at 80 C is hardly observed with a faint trace in slope at this temperature. For much thicker films, neither jump appears in heating experiments. The thickness dependent complex behavior observed in non-equilibrium condition is considered to be some indication of surface and confined effects, because the characteristic film thicknesses coincide with the order of R g .KEY WORDS: Ultrathin Polystyrene Film / Glass Transition / Thickness Jump / X-Ray Reflectivity / Physical properties of systems are strongly affected by symmetry, dimensionality, and the number of constituent particles. Part of such dependences comprises an interesting field of physics, widely known as confined effects. Numerous experimental and theoretical studies have reported many intriguing confined effects on the glass transition of polymeric materials, and therefore glass-forming polymers are recognized to be an excellent example of such systems. As reproducible experimental results are easily obtained, polystyrene (PS) thin films with atomically flat surfaces have been used as standard glass-forming polymer films. For substrate-supported PS films, a large reduction in the glass transition temperature (T g ) dependent on the film thickness is observed for films less than 40 nm thick.1,2 More interestingly, the so-called free-standing PS films showed T g reduction much larger than those of supported films.3,4 Since the free-standing PS films are free from the interaction between the solid substrates, the strong reduction in T g is considered to reflect enhanced mobility inherent in the surface region exposed to air. The positron annihilation technique was used to estimate the free volume in the surface region, and indicated that the effective T g of PS was T g (bulk)-25 C and T g (bulk)-43 C for the surface region to a depth of 5 nm and 2 nm, respectively.5,6 Scanning viscoelasticity microscopy 7 showed enhanced mobility on the PS surface, and subsequent atomic force microscopy measurements confirmed a soft surface region 3-4 nm thick with low T g . 8 Regarding thermodynamical considerations, concentration of the ends of molecules in the surface region was pointed out, 9 suggesting a decrease in polymer density on the surface, subsequently confirmed by simulations. 10,11 Since the reduced density naturally leads to an increase in the free-volume and enhanced mobility of chain segments, several experimental studies on the surface glass transition of PS successfully employed a two-layer 1 or three-layer 5 model where the surface layer is characterized by constant thickness and peculiar physical properties (e.g., density, and viscosity...

High-resolution Rutherford backscattering spectrometry (HR-RBS) and X-ray reflectivity (XRR) are both powerful tools that can be used to investigate thin film structures with the same depth resolution. HR-RBS can be used to analyze low-density contrast films since it reveals the chemical composition in films. The elemental information aids the XRR analysis of films containing localized hydrogen atoms and low-electron-density contrast layers.

Relationship between dislocation multiplication and work hardening of tensile deformed Cu Zn alloys with different grain sizes was investigated. X ray diffraction line pro le analysis was employed to evaluate dislocation parameters. It was con rmed that dislocation multiplication was enhanced with a decrease in the grain sizes. This was mainly caused by GN Geometrically Necessary dislocation, which was characterized by KAM Kernel Average Misorientation in EBSD Electron Back Scatter Diffraction . The strength of dislocation hardening was evaluated from the α value in the Bailey Hirsch equation:The α values were estimated by plotting the ow stress against square root of dislocation density. The α values became smaller with the decrease in the grain sizes, suggesting that the strength of dislocations hardening for unit length of dislocation became smaller. In order to elucidate the origin of the relationship between the grain size and the α values, the in uence of grain size on the fraction of GN dislocation density as well as the outer radius of dislocation strain eld. Whereas the effect of the fraction of the GN dislocation on the α values was small, the outer radius of dislocation strain eld strongly affected the α values.

We investigated effects of a BaTiOIn this study, we find that the critical behaviour of the BaTiO 3 /SrTiO 3 interface is influenced significantly by the surface condition generated by the epitaxial cap layer. It is likely that a change of dimensionality and/or tensile stress at the interface could affect the critical behaviour of this interfacial region.