Recently, various two-dimensional (2D) materials, such as graphene, transition metal dichalcogenides and so on, have attracted much attention in electron device research. The most important characteristic of graphene is its highest mobility of all semiconductor channels at room temperature. However, it is obvious that more than a good mobility characteristic is required to realize the field effect transistor (FET), and intense arguments from various points of view are necessary. In this paper, the issues with Si-metal oxide semiconductor FETs (Si-MOSFET) and the advantage of 2D materials are discussed. The present state of graphene FETs with respect to gate stack formation and band gap engineering is reported. Moreover, based on the density of states (DOS) of graphene extracted using the quantum capacitance (C Q) measurement, it is shown that the electric band structure of graphene in contact with gate insulators or metal electrode deviates from its intrinsic band structure.

The hot deformation behavior of as-cast AZ91 magnesium alloy reinforced by SiC nanoparticles (SiCp/AZ91 nanocomposite) was investigated using hot compression test. Compared with unreinforced AZ91 alloy, peak stress of the SiCp/AZ91 nanocomposite achieved faster and high temperature deformation ability which was enhanced by the addition of SiC nanoparticles. The values of n for the AZ91 alloy and nanocomposite were 6.9 and 4.6, while the values of Q were 207.96 kJ/mol and 184.6 kJ/mol, respectively. The processing map showed the optimum processing conditions for the nanocomposite mainly concentrated at 523–673 K/0.018–0.001 s−1 and the maximum power dissipation efficiency was found to be 36% at a temperature of 673 K and the strain rate of 0.001 s−1. Based on the constitutive equation and processing map, the deformation mechanism for the present nanocomposite should be dominated by the mechanism of dynamic recrystalization.

Mo2Ni3Si–Al2O3 nanocomposite was synthesized using MoO3, Ni, Si, and Al as starting materials by mechanical alloying. The mechanically alloyed powders were consolidated by hot pressing. The morphology and structural evolution of composite powders were investigated by scanning electron microscopy (SEM) and x-ray diffraction (XRD). The microstructure and mechanical properties of the consolidated products were studied in detail. The results showed that Mo2Ni3Si–Al2O3 composite was obtained after 10 h of milling. The reaction mechanism mechanically induced self propagating reaction. The mean grain size of Mo2Ni3Si and Al2O3 after milling for 20 h were 15.9 and 32.4 nm, respectively. The Mo2Ni3Si–Al2O3 composite powders are stable during an annealing at 1000 °C. After consolidation, Mo2Ni3Si–Al2O3 composite has a high density (96.3%) and fine-grain (microns and submicrometer range). The hardness, flexure strength, and fracture toughness of Mo2Ni3Si–Al2O3 composite are 13 GPa, 533 MPa, and 6.29 MPa·m1/2, respectively. Meanwhile, the composite has higher strength at high temperature, and the strength remains stable up to 1000 °C (about 513 MPa).

In this study, a system of triple liquid phases was developed using Li2CO3, Na2CO3, and K2CO3 to improve the densification of the akermanite scaffolds fabricated by selective laser sintering (SLS). The system formed a ternary liquid phase (Li2CO3–Na2CO3–K2CO3) at 399 °C, a binary liquid phase (Na2CO3–K2CO3) at 695 °C, and a unitary liquid phase (K2CO3) at 891 °C during sintering process. The effects of the liquid phases on the sinterability and mechanical properties of the scaffolds were investigated. The fracture toughness and compressive strength is increased by 43 and 152% with liquid phases increasing from 0 to 4 wt%, respectively. This was explained that liquid phases enhanced densification via improving diffusion kinetics and inducing particle rearrangement. In addition, the scaffolds maintained favorable hydroxyapatite (HA) formation ability and cell proliferation ability, which was proved by simulated body fluid (SBF) test and microculture tetrazolium test (MTT), respectively.

The isothermal oxidation experiments were carried out on several new γ/γ′-strengthened cobalt-base alloys Co–Al–W–4Cr–0.02X (X = La, Ce, Dy, Y) at 900 and 800 °C. Due to an appropriate content of additional elements, the change in the morphology occurred and it significantly improved the oxidation resistance compared with those without Cr, among which the one with La elements shows the best oxidation resistance. Multiple oxide layers are also formed during the oxidation process, with CoWO4 and CoAl2O4 phases in the outer layer, and Cr, Al, W, and Co (e.g., Cr2O3) in the middle layer. The inner layer consists of some Al2O3 oxides, while more protective Al2O3 oxide was formed, esp. at the temperature of 800 °C. Both Cr2O3 and Al2O3 oxides were effectively protective oxides, which can prevent the intrusion of oxygen into the alloy substrate. Moreover, a phase transformation (γ/γ′ to γ/Co3W) was observed at the interface between oxide layer and substrate.

The effect of Ta concentration on the fundamental mechanical properties of W–Ta alloys has been studied from first principles study. The lattice constants, the cell volumes, and the formation energies of the W1−x Tax (x = 0.0625, 0.125, 0.1875, 0.25, 0.3125, 0.5, 0.5625, 0.625, 0.75) alloys were calculated. It is shown that Ta alloying in bcc W lattice is an infinite solid solution and the W0.5Ta0.5 have the lowest formation energy. With the optimized geometry and lattice, the elastic constants are calculated and then the elastic moduli and other mechanical parameters are derived. Results show that although the mechanical strength of the W–Ta alloys is lower than that of pure W metal, it is much higher than that of pure Ta metal. On the other hand, the B/G ratio and the Poisson's ratio of the W–Ta alloys is much higher than that of pure W, and even higher than that of pure Ta, indicating that Ta alloying can improve the ductility of bcc W substantially.

Effects of crystal tilt on the determination of the relative positions of different ion columns in compounds such as ferroelectric PbTiO3 are of critical importance, because the displacements of Ti and O relative to Pb correlate directly to the spontaneous polarization and ferroelectric properties. Here a study about the effects of small-angle crystal tilt on the relative image spots positions of different ions in PbTiO3 was carried out under high angle angular dark-field (HAADF) and bright-field imaging for aberration corrected Scanning Transmission Electron Microscope. The results indicate that crystal tilt affects the relative positions of Pb, Ti, and O greatly, and the effects are proved to depend highly on crystal tilt angle and PTO thickness. HAADF image simulations on PbTiO3, SrTiO3, and SrRuO3 indicate that the difference in atomic number is a main contributor to the relative image spot position change of different ion columns when crystal tilts.