Scanning Electron Microscopy Analysis of the Interfacial Failure of Oxide Scales on Stainless Steels and Its Effect on Sticking during Hot Rolling.

Despite various strategies to address sticking failure in stainless steels (STSs), difficulties in understanding its fundamental mechanisms hinder precise solutions during STS fabrication. This study investigated the effect of chromium (Cr) content on the microstructures and failure modes of oxide scales under a tensile load, simulating the hot-rolling process. The dynamic, real-time behavior of crack initiation, propagation, and interfacial delamination in the oxide scales under tension was analyzed using an scanning electron microscopy (SEM) tensile test.

Design of V-Substituted TiFe-Based Alloy for Target Pressure Range and Easy Activation.

Titanium iron (TiFe) alloy is a room-temperature hydrogen-storage material, and it absorbs hydrogen via a two-step process to form TiFeH and then TiFeH. The effect of V addition in TiFe alloy was recently elucidated. The V substitution for Ti sublattice lowers / ratio, where and are the equilibrium plateau pressure for TiFe/TiFeH and TiFeH/TiFeH, respectively, and thus restricts the two-step hydrogenation within a narrow pressure range.

Structural homogeneity and mass density of bulk metallic glasses revealed by their rough surfaces and ultra-small angle neutron scattering (USANS).

The ultra-small angle neutron scattering (USANS) measures the microscale structure of heterogeneity and the scattering from rough surfaces with small scattering volumes can be neglected. But this is not true in amorphous alloys. The small angle scattering from such surfaces is not negligible, regardless of scattering volume.

Flaw-Containing Alumina Hollow Nanostructures Have Ultrahigh Fracture Strength To Be Incorporated into High-Efficiency GaN Light-Emitting Diodes.

In the present study, we found that α-alumina hollow nanoshell structure can exhibit an ultrahigh fracture strength even though it contains a significant number of nanopores. By systematically performing in situ mechanical testing and finite element simulations, we could measure that the fracture strength of an α-alumina hollow nanoshell structure is about four times higher than that of the conventional bulk size α-alumina. The high fracture strength of the α-alumina hollow nanoshell structure can be explained in terms of conventional fracture mechanics, in that the position and size of the nanopores are the most critical factors determining the fracture strength, even at the nanoscales.

Micro-to-nano-scale deformation mechanisms of a bimodal ultrafine eutectic composite.

The outstading mechanical properties of bimodal ultrafine eutectic composites (BUECs) containing length scale hierarchy in eutectic structure were demonstrated by using AFM observation of surface topography with quantitative height measurements and were interpreted in light of the details of the deformation mechanisms by three different interface modes. It is possible to develop a novel strain accommodated eutectic structure for triggering three different interface-controlled deformation modes; (I) rotational boundary mode, (II) accumulated interface mode and (III) individual interface mode. A strain accommodated microstructure characterized by the surface topology gives a hint to design a novel ultrafine eutectic alloys with excellent mechanical properties.

Microstructural analysis of dehydrogenation products of the Ca(BH₄)₂-MgH₂ composite.

The microstructural analysis of the dehydrogenation products of the Ca(BH₄)₂-MgH₂ composite was performed using transmission electron microscopy. It was found that nanocrystalline CaB₆ crystallites formed as a dehydrogenation product throughout the areas where the signals of Ca and Mg were simultaneously detected, in addition to relatively coarse Mg crystallites. The uniform distribution of the nanocrystalline CaB₆ crystallites appears to play a key role in the rehydrogenation of the dehydrogenation products, which implies that microstructure is a crucial factor determining the reversibility of reactive hydride composites.

Development of tough, low-density titanium-based bulk metallic glass matrix composites with tensile ductility.

The mechanical properties of bulk metallic glasses (BMGs) and their composites have been under intense investigation for many years, owing to their unique combination of high strength and elastic limit. However, because of their highly localized deformation mechanism, BMGs are typically considered to be brittle materials and are not suitable for structural applications. Recently, highly-toughened BMG composites have been created in a Zr-Ti-based system with mechanical properties comparable with high-performance crystalline alloys.

Designing metallic glass matrix composites with high toughness and tensile ductility.

The selection and design of modern high-performance structural engineering materials is driven by optimizing combinations of mechanical properties such as strength, ductility, toughness, elasticity and requirements for predictable and graceful (non-catastrophic) failure in service. Highly processable bulk metallic glasses (BMGs) are a new class of engineering materials and have attracted significant technological interest. Although many BMGs exhibit high strength and show substantial fracture toughness, they lack ductility and fail in an apparently brittle manner in unconstrained loading geometries.