One of the challenges in developing a low thermal conductivity material addresses on searching lightweight ceramic without heavy or rare-earth (RE) elements. Mg2Al4Si5O18 interests us for its very low density and complex crystal structure. The first-principle calculations were performed to predict mechanical and lattice thermal conductivity of hexagonal and orthorhombic phases of Mg2Al4Si5O18. According to Debye approximation and the Slack model, the lattice thermal conductivity varies with temperature in 804.6/T and 719.7/T, yielding 2.95 and 2.64 W/(m·K) at room temperature, respectively. The high temperature limits of thermal conductivities are as low as 1.33 and 1.29 W/(m·K). The thermal conductivities of both polymorphs of Mg2Al4Si5O18 are lower than most of RE-containing silicates and zirconates. The present work suggests that Mg2Al4Si5O18 is a promising lightweight ceramic with extremely low thermal conductivity. We also highlight that enhancing complexity of the crystal structure rather than incorporating heavy RE elements may be an alternative wisdom to explore lightweight thermal insulators.

ZrO2:Eu3+ hollow spheres were successfully fabricated with the resin microspheres as the template. The sample characterizations were carried out by means of x-ray diffraction (XRD), scanning electron microscope (SEM), and photoluminescence spectra. XRD results revealed that Eu3+-doped samples were pure t-ZrO2 phase after being calcined at 873 K. SEM results exhibited that this Eu3+ doped ZrO2 was hollow spheres; the diameter and thickness of which were about 450 and 50 nm, respectively. Upon excitation at 394 nm, the orange-red emission bands at the wave length longer than 570 nm were from 5D0 → 7FJ (J = 1, 2) transitions. The asymmetry ratio of (5D0 → 7F2)/(5D0 → 7F1) intensity is about 1.61, 1.26, 1.42, 1.42, 1.40, and 1.38 for the Eu3+ concentration 0.4, 0.7, 1.0, 1.5, 2.0, and 2.5 mol%, respectively. These values suggest that the asymmetry ratio of Eu3+ ions is independent of the doping concentration. The optimal doping concentration of Eu3+ ions in ZrO2 is 1.5 mol%. According to Dexter's theory, the critical distance between Eu3+ ions for energy transfer was determined to be 16 Å.

Morphologically controllable copper sulfide (CuS) nanoneedle, nanowall, and nanosheet networks on copper substrates have been fabricated by a simple, facile, and fast method based on low-temperature chemical vapor deposition through simply adjusting the reaction conditions such as the temperature and flow rate of argon gas. The compositional and structural analyses indicated that all the obtained nano-networks were single-crystalline. And their growths were possibly controlled by a solid–liquid–solid mechanism. The photocatalytic activities of the different shaped CuS nanostructures have been evaluated by their photodegradation on rhodamine B and methylene blue in aqueous phase, which revealed that in both cases the CuS nanoneedles nano-network exhibited better performance than the other two nanostructures.

The effect of interface tailoring by Cu coating carbon nanotubes (CNTs) on the properties of CNTs enhanced copper–tungsten (CNT/Cu–W) composites is investigated. Thermal, electrical, and mechanical properties were measured, and interfacial thermal resistance between Cu and CNT was calculated according to the thermal conductivity curves. CNTs with interface tailoring showed superior dispersion state in the Cu–W composites. When the CNT contents were lower than 0.5 vol%, homogeneous dispersion CNTs and strong interfacial bond between CNTs and Cu had a positive effect on the physical properties of CNT/Cu–W composites. Such interface modification can effectively achieve thermal and electrical conduction, as well as transfer load between CNTs and Cu in the CNT/Cu–W composites. When the CNT contents were higher than 0.5 wt%, the CNT agglomerations became the dominant factor to decrease the physical properties of the composites.

The technologies of brush plating and dealloying were used to treat the surface of rolled copper foil. Zn–Ni and Sn–Zn alloy coatings were prepared. The laws of plating solutions composition and technological parameters on coatings quality were investigated. The results show that with the decreasing of main elements mass ratio or increasing of brush time, thickness and corrosion resistance of Zn–Ni alloy coating increase. With the increasing of brush plating voltage or time, surface roughness of Sn–Zn alloy coating decreases. Turning up brush plating voltage could raise deposition rate of sub-tin and zinc ions and refine surface grains of coating. The angle of dealloying has the significant effect on the roughness of dealloyed Sn–Zn alloy coating. As the dealloying angle increases, surface roughness of dealloyed Sn–Zn alloy coating increases. The contribution of dealloying time to surface roughness of treated coating is obviously larger than that of corrosion solution concentration.

An extruded Mg–8Gd–4Y–1Nd–0.5Zr alloy was preheated at 500 °C for 0.5 h and then subjected to hot compression to a true strain of 0.69 at temperature 450 °C and a strain rate of 0.2 s−1. It is observed that boundaries of small grains (∼3 μm) in the extruded alloy are decorated with irregular-shaped particles; small grains show a weak texture of three main components of $\left\langle {0001} \right\rangle //{\rm{TD}}$ , $\left\langle {11\overline 2 1} \right\rangle //{\rm{ND}}$ , and $\left\langle {10\overline 1 0} \right\rangle //{\rm{ED}}$ . Dynamic recrystallization is concurrent with dynamic precipitation of particles during hot compression, resulting in both a uniform grain structure and a redistribution of particles. The retained particles before compression keep the texture unchanged during compression, leading to the same texture type of $\left\langle {0001} \right\rangle //{\rm{TD}}$ of the compressed alloy as that of the preheated alloy. The compressed alloy exhibits a better aging hardening ability than the extruded alloy. After peak aging, the compressed alloy presents an ultimate tensile strength of 416 MPa, a yield tensile strength of 317 MPa, and an elongation of 2.7%.

The strain hardening effect and dynamic recovery behavior of a Ni-based superalloy are studied by isothermal compressive tests. A new unified dislocation-density based constitutive model is developed to characterize the strain hardening effect and dynamic recovery behavior of the studied superalloy. In the developed constitutive model, some material parameters (yield stress, strain hardening coefficient, and dynamic recovery coefficient) are assumed as functions of initial grain size, deformation temperature, and strain rate. An iterative algorithm is designed to predict the high-temperature deformation behaviors under time-variant hot working conditions. The hot deformation parameters and material parameters can be updated in each strain increment. Comparisons between the experimental and calculated flow stresses indicate that the developed constitutive model can accurately describe the high-temperature deformation behavior of the studied superalloy. Furthermore, the developed constitutive model is also successfully used for analyzing time-variant hot working processes.

In classical twinning theory, the K 2 plane of $\left\{ {11\bar 22} \right\}\left\langle {11\bar 2\bar 3} \right\rangle$ twinning mode was predicted to be $\left\{ {11\bar 2\bar 4} \right\}$ , with a twinning shear of ∼0.22 which was experimentally “confirmed”. However, these twinning elements cannot be reproduced or verified in atomistic simulations. The K 2 plane in the simulations is always (0001), but this K 2 plane would lead to a nominal twining shear of 1.26 which is unrealistically large. In this work, atomistic simulations were performed to investigate the migration of $\left\{ {11\bar 22} \right\}$ twin boundary in titanium (Ti). Shear and atomic shuffles for three different, reported K 2 planes were analyzed in great detail, for the first time. The analyses show that ${K_2} = \{ 11\bar 2\bar 4\}$ leads to very complex shuffles despite the small twinning shear and is unfavorable. If ${K_2} = \{ 11\bar 2\bar 2\}$ , only half of the parent atoms are involved in the shuffling, but the twinning shear is very large (0.96) and is also unfavorable. When K 2 = (0001), the parent atoms are carried to twin positions partly by shear and partly by a simple shuffle. Because shuffling makes no contribution to the twinning shear, the actual twinning shear is 0.66, instead of 1.26. Thus, K 2 = (0001) is the most favorable and the conflict between the simulation results and the classical twinning theory can be reconciled.

In the present work, the effect of pre-ageing temperature and time variations on the mechanical properties and electrical conductivity of the Retrogression and re-aging (RRA) treated 7050 has been investigated. The results reveal that the electronic conductivity and hardness of RRA-treated samples are sensitive to the pre-ageing tempers. The RRA-treated samples with 120 °C/2 h pre-ageing +180 °C/2 h retrogression +120 °C/24 h re-ageing temper can be tailored toward a good combination of strength and elongation, while the electrical conductivity of re-ageing samples is also higher than that of 120 °C/24 h pre-ageing RRA-treated samples. With an intermediate pre-ageing temperature of 80 °C/24 h RRA-treated samples possess a higher re-aged electronic conductivity, while no significant differences can be found between hardness of 120 °C/2 h and 120 °C/24 h pre-ageing RRA-treated samples. The variation of hardness and electronic conductivity during retrogression depends on the pre-ageing tempers. For under-aged sample, the retrogression hardness appears a stage of hardness increasing followed by a further decrease in hardness results, owing to disappearance of dissolving stage of fine GP zone and η′ phase during pre-ageing.