The large volume production of flexible electronics by solution based roll-to-roll (R2R) manufacturing technologies is a promising upscaling strategy for the organic electronics industry. Typical optoelectronic devices like organic light emitting diodes (OLEDs) consist of a complex stack of functional layers. Solution deposition of these structures eliminates the need for expensive vacuum processing. This contribution presents approaches for solution based R2R production methods of functional OLED layers on flexible polymer substrates. The development of a R2R line with two slot-die coating stations is discussed which can deposit two uniform layers consecutively in a single run (“tandem coating”) at web speeds up to 30 m/min. Furthermore, it offers the unique feature that there is no contact between the rollers and the top side of the substrate where the functional coating is deposited. Thereby, an important source of particle contamination and other damage to the device is eliminated. In addition to continuous deposition, stripe and intermittent coating techniques have been developed, allowing the production of patterned layers. Finally, examples will be shown of OLEDs where two functional materials are deposited by R2R processing from solution.

The unloading part of a load–displacement curve from instrumented indentation tests is usually approximated by a power law (Oliver and Pharr model), where the load is the dependent variable. This approach generally fits well the data. Nevertheless, the convergence is occasionally quite questionable. In this regard, we propose a different approach for the Oliver and Pharr model, called the inverted approach, since it assigns the displacement as the dependent variable. Both models were used to fit the unloading curves from nanoindentation tests on fused silica and aluminum, applying a general least squares procedure. Generally, the inverted methodology leads to similar results for the fitting parameters and the elastic modulus (E) when convergence is achieved. Nevertheless, this approach facilitates the convergence, because it is a better conditioned problem. Additionally, by Monte Carlo simulations we found that robustness is improved using the inverted approach, since the estimation of E is more accurate, especially for aluminum.

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.

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.

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.

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.

Indentation relaxation test is investigated from theoretical and experimental points of view. Analytical expressions are derived based on the conical indentation of a homogeneous linear viscoelastic half space. Two loading kinetics prior to the hold displacement segment are studied—i.e., constant displacement rate and constant strain rate. Effects of loading procedure on measured relaxation behavior are considered. It is pointed out that a constant strain rate loading is required to perform depth-independent relaxation measurements and the strain rate affects the relaxation spectrum up to a critical time constant. Few experiments on poly(methyl methacrylate) are then performed to check the consistency of the analytical results. Some experimental limitations are also discussed. Good agreement is found between analytical calculations and experimental measurement trends, especially for the constant strain rate loading effect on the measured relaxation behavior.

A well-designed hybrid welding process for resistance plug welding (RPW) was conducted based on TRIP980 high-strength steel and SPCC low-carbon steel. The effects of welding current, welding duration time, electrode pressure and filler diameter on the shear tensile failure loading of the joint were systematically investigated and the related optimal welding parameters were accordingly obtained. The microstructure and mechanical properties of the joint were subsequently analyzed. The experimental results indicated that the welding parameters of welding current, filler diameter, and welding duration time and electrode pressure influencing the shear tensile failure loading of the joint are quite vital. This kind of joint possesses a rounded rectangular nugget and transition region. The atomic diffusion results in the firm joint, the metallurgical bonding between filler and base material is realized through the RPW technique.

Precipitates and grain sizes in non-oriented silicon steel samples, which were hot-rolled (HR), continuously annealed (CA), and stress-relief-annealed (SA), were characterized using scanning electron microscopy (SEM) equipped with electron back-scattered diffraction. The average grain sizes of the HR, CA, and SA samples were 28, 46, and 46 μm, respectively. SEM observations revealed that the precipitates were mainly dispersed inside grains in the HR and the CA samples, but mainly at grain boundaries in the SA sample. The density of precipitates was highest in the SA sample and lowest in the HR sample. Precipitates at the grain boundaries, which were identified as manganese sulfides, were nearly spherical, their diameter ranging from 0.3 to 0.7 μm. We calculated the pining force exerted by grain-boundary precipitates and found that it outweighed the driving force of the grain growth that was controlled by boundary curvature.

A “RE-free” and I-phase-containing Mg–8Sn-based alloy system was developed and successfully fabricated through the equal channel angular pressing (ECAP) process. The influence of the Zn/Al mass ratio on the microstructures and mechanical properties of the as-ECAPed Mg–8Sn–(5,6,7)Zn–2(wt%)Al alloys was investigated using an optical microscope, an X-ray diffractometer, a scanning electron microscope, a transmission electron microscope, and a universal testing machine. Grain size, dynamic recrystallization behavior, and texture were found to be greatly affected by the Zn/Al mass ratio. Furthermore, the ultimate tensile strength (250 MPa) and elongation (14.5%) of the alloy with a Zn/Al mass ratio of 3 were considerably increased compared to those of the as-ECAPed alloys with Zn/Al ratios of 2.5 and 3.5 (ultimate tensile strength and elongation of 215 MPa and 13% and 184 MPa and 10%, respectively). This significant enhancement was attributed to extensive grain boundary strengthening, precipitation strengthening, and higher work hardening capacity as well as texture randomization. The strength and ductility of the as-ECAPed alloys are also discussed in terms of the I-phase and Mg2Sn formation.

We address the competitive precipitation and coprecipitation of three types of secondary phases, i.e., Cu-rich precipitates (CRPs), reverted austenite (RA), and alloyed carbide, in a high-strength low-alloy steel with austenite reversion treatment at 675 °C by using electron back-scatter diffraction, transmission electron microscopy, and atom probe tomography. There is a strong competitive diffusion of Ni and Cu participating in austenite reversion and Cu precipitation with the fact that no CRPs are detected in and around the RA. Meanwhile, there is also a strong competitive diffusion of austenite stabilizing element Ni and carbide-forming elements Cr and Mo into the pre-existing C-rich zone, leading to the formation of nonequilibrium alloyed carbide deviating from the stoichiometric composition. On the other hand, the alloyed carbide and CRPs provide constituent elements for each other and make the coprecipitation thermodynamically favorable. The knowledge on the interactive formation of these three features provides versatile access to tailor the distributional morphology of CRPs, RA, and alloyed carbide via a multistage heat treatment and thus realize their beneficial effect on strength and toughness.

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.

Hill’48 yield function has been widely used to describe the anisotropic behaviors of material in FE simulation of tube and sheet metal forming process. To obtain the material behaviors of small-sized H96 brass extrusion double-ridged rectangular tube (DRRT) in bending process, an inverse method combining response surface method and three-point bending was proposed to identify the parameters of Hill’48 yield function. It was found that comparing with Hill’48 yield function only considering the normal anisotropy and Mises yield function, Hill’48 yield function with the identified parameters performs the best in reproducing the material behavior of H96 brass DRRT in three-point bending process. And then Hill’48 yield function with the identified parameters was also adopted in the FE simulations of rotary draw bending of DRRT. It was observed that the prediction accuracy of cross sectional deformation of DRRT in rotary bending process was improved effectively by using Hill’48 yield function with the identified parameters. This proves that the proposed inverse method is suitable to the real forming process.

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.

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.

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.

The erosion behavior of a directionally solidified Fe–B alloy containing 3.5 wt% B in the different velocities of flowing liquid zinc is investigated by X-ray diffraction and scanning electron microscopy to clarify the effect of interaction between Fe2B and the erosion products on erosion performance using a rotating-disk technique. The results indicate that the Fe–B alloy erodes at a low and steady rate in flowing liquid zinc. The microstructure of erosion layers of the directionally solidified Fe–B alloy depends on the orientation relation between the growth direction of Fe2B phase and the erosion surface. When the growth direction of Fe2B is perpendicular to the erosion surface, the Fe2B and the erosion compounds form a compact and stable combining layer that effectively inhibits the erosion of flowing liquid zinc and further improves the erosion resistance of Fe–B alloy.

To investigate the recrystallization behavior of large sized Nb–V microalloyed steel rods during thermomechanical controlled processing (TMCP), a series of isothermal hot compression tests were conducted on a Gleeble 1500 thermomechanical simulator. The kinetics and microstructure evolution models of dynamic recrystallization, static recrystallization, metadynamic recrystallization and the grain growth model of the tested steel were developed. Based on the developed models, a finite element (FE) model coupled with the recrystallization behavior of large sized Nb–V microalloyed steel rods during TMCP was established. Then, the distributions and evolutions of recrystallization fraction and grain size during the whole deformation process are obtained and analyzed. Finally, the predicted results were compared with experimental ones, and they show good agreement. This illustrates that the recrystallization models of the tested steel are valid and the developed FE model of large sized Nb–V microalloyed steel rods during TMCP is effective.

Some time ago, we reported the synthesis of bixbyite-type V2O3, a new metastable polymorph of vanadium sesquioxide. Since, a number of investigations followed, dealing with different aspects like electronic and magnetic properties of the material, the deviation from ideal stoichiometry or the preparation of nanocrystals as oxygen storage material. However, most of the physical properties were only evaluated on a theoretical basis. Here, we report the lattice dynamics and physical properties of bixbyite-type V2O3 bulk material, which we acquired from physical property measurements and neutron diffraction experiments over a wide temperature range. Besides attributing different possible orientations of the magnetic moments for V1 and V2 to the identified antiferromagnetic (AFM) ground state with a Néel temperature of 38.1(5) K, we use a first order Grüneisen approximation to determine lattice-dependent parameters for the relatively stiff cubic lattice, and, amongst others identify the Debye temperature to be as low as 350 ± 65 K.