A novel stainless steel porous twisted wire material (PTWM) is made of twisted short wires by compaction followed by vacuum high-temperature solid-phase sintering. The twisted short wires are fabricated by using a self-developed rotary multicutter tool to cut stainless steel wire ropes. The PTWMs with 46–70% porosities have been investigated in terms of porous structures and Charpy impact behavior. The PTWMs with spatial composite intertexture structures exhibit interconnected open-pore microstructures with a variety of shapes and sizes. The pore size distributions became convergent with decreasing porosities. The span of pore distribution of the PTWM with a diameter of 90 μm was half than that of the PTWM with a diameter of 160 μm under 65–66% porosity. The impact toughness of the former is 2.6 times than that of the latter. By increasing the porosity from 46 to 70%, the impact toughness decreases from 17.9 to 9.1 J/cm2. Macroscopically integral failure-morphologies of the PTWMs present mixed ductile–brittle failure mechanisms, but microscopic impact deformation and failure mechanisms mainly show the ductile failure and fracture of pore skeletons. The PTWMs demonstrate complex energy absorption mechanisms.

Recently, in situ characterization methods have attracted increasing attention, especially in organic photovoltaics (OPV) field, since they provide greater insight into the mechanism of film formation, thus help to identify optimized processing conditions used to process the most efficient organic bulk-heterojunction thin films. In combination with various powerful X-ray-based characterization methods, several studies observed the morphological changes under the influence of different processing conditions. In this review, we summarize the fundamentals and implementation of X-ray-based and optical characterization methods, utilized in in situ mode and introduce the reader a better overview of the information acquired from a given technique in terms of microstructure formation in OPV. While we give a chronological development of in situ characterization methods in the field of OPV, we discuss the interplay between thermodynamics of solutions and drying kinetics of different types of organic blends.

Melt-SHS (self-propagating high-temperature synthesis), based on the SHS process and oxide reaction method, was used for preparation of TiB2/Al composites. The mass ratio of two reactants, Ti powder/TiO2, in initial powder mixture was varied from 0:1 to 1:0. The results showed that the 5 wt% TiB2/Al composites could be successfully produced by a reaction of aluminum powder, TiO2, and B2O3 in Al melt at 950 °C, while the reaction rate was slow. The addition of titanium powder helps to reduce the content of Al2O3 and destroy the coating structure of Al2O3 covered TiB2 particles, which leads to the acceleration of reaction process and improvement of particle concentration. A significant improvement was that TiB2 particles were dispersively distributed when the mass ratio of Ti powder/TiO2 was 2:3. As a result, the 5 wt% TiB2/Al composites fabricated by melt-SHS process with modified reactants ratio showed excellent tensile properties with the ultimate tensile strength as high as 114.24 MPa. Besides, the composite also showed superior ductility.

The effect of longitudinal alternating current (LAC) on the growth of the interfacial layers of the copper cladding aluminum (CCA) composite flat bar during isothermal annealing was investigated. The results showed that the application of LAC could remarkably inhibit the growth of interfacial compounds as well as improve the interfacial bonding property of the CCA composite. When the CCA flat bars were annealed at temperatures ranging from 723 to 773 K for 1 h with a LAC density higher than 0.625 A/mm2, the total thickness of the interfacial compound layers was reduced by more than 75% in comparison to CCA flat bars annealed without LAC. The reduction of the thickness of the interfacial layers resulted in an improvement of the bonding strength of the CCA composite. The mechanism of the inhibition effect was that the application of LAC could accelerate the vacancy annihilation in component metals.

Several recent X-ray photon correlation spectroscopy works have reported an anomalous atomic dynamics in hyperquenched metallic glasses. Here, we compare and contrast these microscopic dynamics with that found in a Zr44Ti11Ni10Cu10Be25 bulk metallic glass, prepared with a cooling rate some 6 orders of magnitude lower. In both cases, structural relaxation in the glass is governed by internal stresses, giving rise to highly compressed density correlation functions. Differently from the fast aging reported in previous studies, here the atomic dynamics displays a slow linear atomic-level aging, while not affecting the shape parameter. Traditional macroscopic phenomenological models fail to capture the temperature dependence of the microscopic structural relaxation time, suggesting a length scale dependence of the aging. Interestingly, the dynamics does not seem to be affected by the presence of a low percentage of frozen nanocrystals and displays a temperature dependence similar to that observed in macroscopic viscosity measurements.

Grain boundary segregation can reduce the driving force for grain growth in nanocrystalline materials and help retain fine grain sizes. However, grain boundary segregation is enthalpically driven, and so a stabilized nanocrystalline state should undergo a disordering process as temperature is increased. Here we develop a Monte Carlo-based simulation that determines the minimum free energy state of an alloy with a strong tendency for grain boundary segregation that considers both different grain sizes and a large solute configuration space. We find that a stable nanocrystalline alloy undergoes a disordering process where grain boundary segregated atoms dissolve into the adjacent grains and increase the grain size as a function of temperature. At a critical temperature, the single crystal state becomes the most preferred. Using this method, we are able to determine how the grain size changes as a function of temperature and produce equilibrium phase diagrams for nanocrystalline alloys.

The traditional macro-scale form of dynamic indentation measures the dynamic deformation behavior of a material by simulating impact conditions. Similarly, the nano-impact indentation technique, with small-scale contacts and high spatial resolutions, is a novel technique for obtaining mechanical properties of materials at dynamic strain rates (>102 s−1). Nano-impact hardness values display a decreasing trend or size effect that continues for several micrometers of indentation depth, compared to the primarily sub micrometer depth range of size effect in quasi-static nanoindentations. For the first time, the factors behind the enhanced size effects for dynamic micro-scale indentations have been investigated by the current work: non-uniform loading and resulting instability using strain rate profiles, plastic wave behavior during loading using resistance force versus indentation depth profiles, quantification of energy of the dynamic plastic wave, and localization of impact strain using electron backscattered diffraction (EBSD) mapping of the strain affected vicinity of indentation imprints.

Cs2LiYCl6 (CLYC) is a commercial scintillator material having good energy resolution and dual gamma/neutron detection capabilities. CLYC crystals currently used in detectors are grown by the vertical Bridgman method. Boules grown from stoichiometric melts, however, often contain secondary phases, Cs3YCl6 and LiCl, at the beginning and end of the crystal, respectively, suggesting that this composition is incongruently melting. Since no phase diagram containing CLYC existed in the literature prior to this study, the Cs2YCl5–LiCl phase diagram was explored. Several crystals were then grown from various melt compositions. As predicted from the phase diagram, a starting composition of around 60 mol% LiCl did not produce Cs3YCl6 and maintained a low concentration of LiCl.

In this paper, drop-weight impact test was carried out on an integrated composite sandwich panel of aluminum honeycomb and epoxy resin to investigate its failure modes and typical force–displacement curves, and the influences of different parameters on plateau phase duration time, nominal stress, and energy absorption capacity were analyzed. Dynamic impact test results indicated that this integrated composite sandwich panel had good integrality, stability, and energy absorption capacity. The force–displacement curves of flat-bottom impactor and gradual impactor respectively had seven and five phases. Impact velocity, impactor shape, and specimen thickness had significant influences on the plateau phase duration time, nominal stress, and energy absorption capacity of the composite panel. It can be found from our results that the mechanical properties of the integrated composite sandwich panel were superior to those of traditional sandwich panels.

In this study, the buckling behaviors of single-walled carbon nanocones (SWCNCs) under bending at finite temperatures are predicted using a proposed multiscale quasi-continuum approach based on the temperature-dependent higher order Cauchy–Born (THCB) rule. The hyper-elastic constitutive model is derived exactly in the context of the higher order gradient theory that incorporates the details of the interatomic interaction. The numerical simulations for the deformation of SWCNCs are implemented using the developed meshless computational framework based on moving least-squares interpolation, which can precisely reproduce the deformation process and buckling patterns of SWCNCs under bending. The underlying correlations of the critical bending angle with respect to the geometry of SWCNCs and temperature are revealed by the numerical results. Furthermore, our simulation captures the transformation from the local to the global buckling process of SWCNCs, accompanied with an average strain energy jump. Our results correspond with previous studies.

NiAl-based nanocomposites were successfully fabricated by mechanical alloying proceeded vacuum-hot-pressing sintering, and the mechanical and tribological properties of the NiA–NbC composite were investigated. The results show that the nanostructured powder particles with the average size around 5 nm were successfully obtained by a high-energy-ball mill. After sintering, the composites were consisted of B2-ordered NiAl and NbC second phase, and the crystalline size of the NiAl phase was about 20 nm. The relative density, hardness, and compressive strength of nanostructured NiAl materials increased with increasing the Nb content, which can be attributed to the second phase hardening effect of in situ formed NbC particulates and fine grain strengthening of nanocrystalline NiAl phase. Thereafter, the friction coefficient of the NiAl–3NbC composite was lowered by the addition of silver and that is significantly lower than the NiAl intermetallic compound and NiAl–3NbC composite at elevated temperatures, which was attributed to the lubricating films formed in sliding process at elevated temperatures. While the wear rates of NiAl–3NbC–10Ag composites are higher than that of the NiAl–3NbC composites at each test temperature, especially at 500 °C and 700 °C, which might be attributed to the phase variations on the worn surfaces of the composites.

Accumulative roll bonding (ARB) process was used to develop Mg–6% Zn/Al and Mg–6% Zn/anodized–Al multilayered composites. Microstructural characterization was done using scanning electron microscopy, energy-dispersive X-ray spectroscopy, electron backscattered diffraction, and transmission electron microscopy. An average grain size measured in the roll-bonded layers of Al, anodized Al, and Mg–2% Zn was found to be 1.8 μm, 1.6 μm, and 0.6 μm, respectively. Phases Al17Mg12, AlMg4Zn11, and Al2O3 after 5-pass of ARB were confirmed by X-ray diffraction analysis. The Mg–6% Zn/Al and Mg–6% Zn/anodized Al composites exhibited tensile strengths ∼252 MPa and ∼256 MPa, respectively, after a 5-pass ARB process. Hardness of the individual layers of composite increased linearly with an increase in the number of ARB passes. Fractographs of the multilayered composite illustrated the ductile failure in Al and anodized Al layers and transgranular brittle fracture in Mg–6% Zn layers.

The aqueous corrosion resistance of TiC–Ni3Al based cermets was examined with the specific aims of assessing the influence of both the raw materials and the test methods, using a 3.5 wt% NaCl containing solution. The effects of W contamination in the ceramic phase was investigated using a single-phase ceramic, with and without W, and with a stoichiometric intermetallic Ni3Al binder. The influence of the electrolyte O2 content was examined for TiC cermets with 30 vol% binder, for both the stoichiometric composition and sub-stoichiometric variants, containing either Zr and B (alloy IC50) or Zr, B and Cr (alloy IC221) additions. Electrochemical measurements were matched with chemical and microstructural analyses at various stages of oxidation, and the rate of material loss in combination with the corrosion mechanisms were identified. The effects of O2 concentration were most significant for the TiC based cermets with Ni3Al due to the diffusion controlled nature of the reaction.

The purpose of this work is, based on CAFE method, to study the microstructure evolution and optimize the quality of the large-scale titanium slab ingot during EBCHM. The nucleation parameters of the microstructure simulation of titanium ingot are determined based on one of the actual experimental results. For the determined parameters, our theoretical results are agreement with other experimental results. The effects of pouring temperature and pulling speed on the microstructure are presented based on CAFE method. The quantitative analyses of the simulated results show that with the pulling speed increasing, the number of grains decreases, whereas the mean grain radius increases under identical thermal condition; with the pouring temperature increasing, the mean grain radius increases under the given pulling speed. Our results are very important to obtain the optimal structure of the ingots by controlling pulling speed and pouring temperature.