Under electrochemical cycling, stress intensification and relaxation within small volumes at the lithium/solid-state electrolyte (SSE) interface are thought to be critical factors contributing to mechanical failure of the SSE and subsequent short-circuiting of the device. Nanoindentation has been used to examine the diffusion-limited pressure lithium can support in the absence of active dislocation sources at high homologous temperatures. Based on the underlying physics of this deformation mechanism, a simple perturbation model coupling local current density, elastic stress, and diffusional creep relaxation is introduced. Combining this analysis with the indentation results, it is possible to describe a defect length scale which is too large for effective diffusional creep relaxation, but too small for efficient dislocation multiplication. In this instance, the properties of the SSE may become critical, and relevant indentation results of the SSE are described. The final outcome of the proposed analysis is a newly developed deformation mechanism map.

A novel tetragonal B2CO structure (tP16-B2CO), formed by strong covalent sp2–sp3 B–C and B–O bonds, was predicted with aid of an unbiased structure searching method. With the energy lower than those of previously proposed candidates, except oI16-B2CO, tP16-B2CO was identified as the thermodynamic metastable phase for B2CO compound. The elastic matrix and phonon dispersion spectra declare that tP16-B2CO is mechanically and dynamically stable. The electronic band structure calculation at ambient pressure and a series of high pressure has manifested the indirect semiconducting and band gap increases first and then decreases with pressure increases. The calculation of mechanical properties such as hardness and stress–strain relations of tP16 structure revealed its common hard nature with high hardness of 23.19 GPa and anisotropy with the max stress along [001] is far higher than that along [100].

[K0.5Na0.5NbO3]1−x[BaNi0.5Nb0.5O3−δ]x (KNBNNO, 0 ≤ x ≤ 0.3) films have been fabricated on different substrates for the first time, using a modified chemical solution deposition method. The microstructure, optical properties, ferromagnetism, and substrate effects of KNBNNO films were assessed, and we found that BaNi0.5Nb0.5O3−δ (BNNO) content was a key factor in determining the properties of the final products. The lower band gap of KNBNNO is due to the band-to-band transition from hybridized Ni 3d and O 2p to Nb 4d states. Moreover, with increasing x from 0 to 0.3, the magnetism transition process of the samples from diamagnetism to ferromagnetism may originate from the competition between ferromagnetic exchange interactions in Ni2+–VO2−–Ni2+ and superexchange interactions in Ni2+–Ni2+. Notably, absorption behaviors in the visible light wave band for KNBNNO films have been realized, which makes it possible to use KNBNNO films for perovskite solar cell applications.

Polyhedral YVO4: Ln3+ (Ln = Eu, Sm, Yb/Er, Yb/Tm) microcrystals were fabricated via a facile sol–gel auto-combustion method using NH4VO3 as vanadium source in the presence of glycine. The X-ray diffraction patterns were well matched with pure YVO4, and the doped lanthanide ions did not change the host structure. The YVO4 microcrystals annealed from 500 to 1000 °C for 3 h were polyhedral and ranged in particle size from 0.1 to 2 μm. The luminescence properties of YVO4: Ln3+ (Ln = Eu, Sm, Yb/Er, Yb/Tm) samples indicated that all of the YVO4: Ln3+ samples exhibited typical emission spectra of Ln3+ cations, suggesting that the Ln3+ cations were well doped in YVO4 and could be excited efficiently through matrix absorption. In addition, the corresponding mechanisms of emission and energy transfer in the YVO4: Ln3+ are proposed.

Flexible electrode is an indispensable component of emerging portable, flexible, and wearable electronic devices. Although various flexible electrodes with different dimensions and functions have been explored, developing a new electrode material with excellent mechanical reliability and superior electrical performance remains a challenge. Here, a graphene-covered Cu composite electrode film with a total thickness of ∼100 nm is successfully fabricated onto a flexible polyimide substrate by means of a series of assembly methods including physical vapor deposition, chemical vapor deposition, and transfer technique. The composite electrode film on the flexible substrate exhibits evidently enhanced tensile strength, monotonic bending, and repeatedly bending fatigue reliability as well as electrical performance compared with that of the bared Cu film electrode. Such excellent mechanical performances are attributed to the role of the graphene coating in suppressing fatigue damage formation and preventing crack advance. It is expected that the chemical vapor-deposited graphene-covered Cu composite electrode would extend the potential ultrathin metal film electrode as the innovative electrode material for the next-generation flexible electronic devices.

In this work, two types of zinc adipate β-nucleating agents, Adi-Zn(OH)2 (1:1) and Adi-ZnO (1:1), for polypropylene (PP) were prepared and their performances were evaluated and compared with commercial β-nucleating agent (named CNA). Results showed that Adi-Zn(OH)2 (1:1) was more effective in promoting PP to form β-crystals and improving the impact strength of PP in the range of nucleating agent addition (0–0.4 wt%). Based on these findings, the ratio of adipic acid to zinc hydroxide and the nonisothermal crystallization kinetics of the optimum ratio of adipic acid to zinc hydroxide were systematically studied; results showed that at 0.2 wt%, Adi-Zn(OH)2 (1:2), the nucleated PP displayed the highest impact strength, which was 2.6 times that of pure PP and 42% higher than that of CNA. Besides, Adi-Zn(OH)2 (1:2) could also afford to induce the formation of a high content of β-crystals and shorten the crystallization half time (t1/2) and accelerate the crystallization of PP.

We report on enhanced mechanical, tribological, and surface-wettability characteristics of polymeric films dispersed with inorganic fullerene (IF)-type tungsten disulfide (WS2) nanoparticles derived through a two-step hydrothermal route. Imaging through transmission electron microscopy suggests the occurrence of polyhedral cage-like structures with a visibly nonspherical hollow ranging 55–75 nm. The mechanical stability of IF-type WS2 dispersed in polyvinyl alcohol (PVA) gets improved with increasing nano-inclusions, and upto 6 wt% loading. As compared with nanosheets, the IF-WS2 in PVA at the critical loading offers nearly 28.6, 33.6, and 42% respective improvements as regards, breaking stress, elongation at break, and toughness. Moreover, Stribeck curves in the mixed lubricating regime have revealed a nearly ∼80% reduction of coefficient of friction (COF) due to inclusion of IF-type WS2 in PVA. In the hydrodynamic region, the COF is drastically lowered from a typical value of 0.55 to 0.15 at the maximal sliding velocity with nanoparticle loading and despite the fact that the tribo feature gives a rising trend for a particular curve. Furthermore, exhibiting a progressive increase in water contact angle, a clear transition from the hydrophilic (∼64°) to hydrophobic (∼107°) surface of the nanocomposite films has been witnessed after inclusion of nano IF-WS2. An increased hydrophobicity and lowered surface adhesion and COF values along with marginal drop in surface energy are ensured in the investigated specimens. Investigation of responsive tribological and wetting–dewetting transition would find scope not only in coating and textile industry but also in smart miniaturized components.

Flexural and thermomechanical properties of the epoxy-based carbon fiber composites (CFCs) on addition of single and binary nanoparticles (nanoclay and graphene) have been investigated. It was found that nanoclay acts more effectively in increasing the stiffness of the CFCs, whereas graphene is more effective in achieving higher strength. Nanoclay-added samples exhibited highest flexural (64.5 GPa) and storage (25.3 GPa) modulus among all types. Graphene-added samples showed highest improvement (by 21%) in flexural strength and exhibited most stable thermomechanical properties with highest energy dissipation capability (3.1 GPa loss modulus) in flexural test and dynamic mechanical analysis (DMA), respectively. By contrast, addition of binary nanoparticles reduced the stiffness and significantly increased the strain to failure (42%) of the composites. Optical microscopy and scanning electron microscopy indicated that addition of nanoparticles significantly reduced delamination and matrix cracking of the CFCs because of strong interfacial bonding and toughened matrix, respectively.

An analysis of indentation cyclic behavior of polymers is carried out with the aim to tackle time-dependent behavior of polymer at several time scales by one test. The method consists in cycling the load between a positive close-to-zero value and a maximum peak value (10 mN in this study) for long time with constant loading rate. The short time scale is characterized through the instantaneous elastic modulus determined from reloading curves at each cycle. The advantages of determination of instantaneous elastic modulus from reloading instead of commonly used unloading curves are discussed. The energy dissipation describes viscoelasticity and plasticity at the time scale of one cycle. The evolution of both parameters with cycles along with the cyclic creep describes the long-time viscoelasticity. The cyclic indentation behavior of poly(methyl methacrylate), PR520 epoxy, and high-density polyethylene (HDPE) polymers is analyzed, and a comparison with the macroscopic cyclic behavior of HDPE is presented.

Deformation twins have a major role in the microstructure evolution of hexagonal close packed (HCP) metals. Voids are common defects in metals and have a significant impact on their properties. In this work, using molecular dynamics, a tension simulation of single-crystal titanium (Ti) with different void sizes under uniaxial stress conditions was performed. The results showed that the evolution and dominance of the $\left\{ {10\bar{1}2} \right\}$ twin system using the Henning potential was not consistent with the Schmid criterion when the single-crystal Ti contained void defects. From a microscopic perspective, the authors analyzed the relationship between the nucleation and growth of twins and the emission of dislocation loops. The authors found that the existence of voids not only contributes to the emission of dislocation loops but also hinders the movement of these loops. With the increase in void size, the peak dislocation density of ${1 \over 3}\left\langle {\bar{1}100} \right\rangle$ partial dislocation loops decreased. This work is helpful to further investigate the nucleation and evolution of tension twins and to form an effective growth criterion for twins to study the twinning process of HCP metals during plastic deformation.

Effects of adding different amounts of SiCp on the microstructure and mechanical properties of the as-cast and as-extruded Mg–7% Zn–1.5% Cu (ZC71) alloys were studied. The as-cast ZC71 alloy consisted of α-Mg phase that encircled with the MgZnCu and Mg(Zn,Cu)2 intermetallics. Hot extrusion has led to a grain-refined structure with distributed intermetallics along the extrusion direction. Adding SiCp decreased the grain size values for the as-extruded composites. The Vickers hardness values increased with SiCp addition for both conditions. The ultimate tensile strength and tensile elongation (El%) values reached the optimum level with 5 wt% SiCp addition. More SiCp additions led to more agglomerations and decrement in strength and elongation. The yield tensile strength also increased with SiC additions. Adding 5 wt% SiCp changed the brittle fracture to the more quasi-cleavage. Hot extrusion altered the fracture mode to more ductile for all composites.

ZL104 alloy foam and ZL104 alloy/aluminum fiber composite foams with a porosity of 71–90% were prepared by an infiltration casting method. The pore structure and the sound absorption properties of these two kinds of foams were studied. The results show that fibers partially embedded in the porous pore walls and partially extending out of the pore in the composite foams. The sound absorption coefficient of the foams has a sound absorption peak and a sound absorption trough with increasing frequency. The fiber composite foam possesses better sound absorption properties compared with the alloy foam. As porosity, fiber diameter, and fiber content increases, the average sound absorption coefficient of the composite foam first increases and then decreases. The average sound absorption coefficient (0.88) of the composite foam with a fiber content of 5 vol%, a fiber diameter of 0.1 mm, and a porosity of 82% increased 10% compared with that of the alloy foam. The surface roughness and specific surface area of the foam increase after fiber compounding, and the sound wave drives the fibers to vibrate to enlarge the consumption of sound energy.

For achieving flame-retardant AZX912 magnesium alloy with superior mechanical properties, cast ingots were solution-treated at different temperatures of 420–525 °C prior to extrusion at 280 °C. With increasing solution treatment temperature, brittle Al2Ca intermetallic compound changed from a network-like morphology to a spheroidized shape, with an increase in hardness and became unbroken during extrusion. As the solution treatment temperature increased, cracking of Al2Ca particles during tensile deformation tended to be restricted due to hardening and spheroidizing behaviors, and tensile elongation of extruded alloys significantly enhanced from 11.2 to 19.2%. High mechanical strength was maintained with an improvement in ductility when increasing the solution treatment temperature up to 510 °C. The extruded alloy solution-treated at 510 °C exhibited a superior balance between mechanical strength and ductility, with a high ultimate tensile strength of 367 MPa and a good elongation of 16.8%.