The coupling between smoothed particle hydrodynamics (SPH) and finite element method (FEM) is an effective approach for the simulation of impact dynamics. An alternative algorithm for the treatment of contact problem between SPH particles and finite elements was employed. Background particles were assigned in the position of finite element nodes, and the contact forces on SPH particles and finite element nodes were calculated with the same approach as SPH particles to particle contact algorithm. The contact force was added to the momentum equation for SPH and dynamic equation for FEM respectively. Using the SPH-FEM contact algorithm, the axial impact between two bars and the perforation of a cylindrical steel projectile impacting a plate target were simulated, where the Johnson-Cook material model with damage effect and Grüneisen equation of state were employed. The computed results showed good agreement with the experimental data.

Combining high-energy ball milling and high-pressure high-temperature technique, high-dense ZrN-ZrB₂ nanocomposites have been synthesized using Zr and h-BN powders as raw materials. The structures of product materials were studied through X-ray diffraction, high resolution transmission electron microscopy and Raman spectroscopy measurements. The result showed that only ZrN_x can be synthesized during mechanical alloying process, which can be explained by the thermodynamics and kinetics of reaction of Zr atoms with N and B atoms. ZrN-ZrB₂ nanocomposites synthesized at 5 GPa and 1 300 ℃ using 10 h ball-milled powder mixture show excellent mechanical and electrical properties. The microhardness, thermal expansion coefficient and thermal coefficient of resistivity of ZrN-ZrB₂ composites are 17 GPa, 7.57×10^-6 ℃^-1 and 8.846×10^-4 ℃^-1, respectively.

Carbon-encapsulated nickel nanoparticles (CENNPs) with core-shell structure were synthesized by detonation method using homemade composite explosives with negative oxygen balance. The detonation chemical reaction was initiated by a nonel tube detonator in a closed explosion vessel filled with nitrogen gas. X-ray diffraction (XRD), X-ray fluorescence (XRF), transmission electron microscopy (TEM) with selected area electron diffraction and Raman spectrum techniques were used to characterize the as-obtained detonation products. The XRD and XRF analysis showed that the detonation products mainly consisted of the well-crystallized face-centered cubic nickel nanocrystals, carbon and other microelement. TEM showed that most nanoparticles are made up of a nickel core with the size of 10~25 nm and a carbon shell with the thickness of 1~2 nm. The Raman spectrum analysis indicated that the coating carbon shell is mainly composed of graphite and amorphous carbon. Furthermore, the possible formation mechanism for CENNPs were also discussed.

High pressure and temperature pretreatments were employed for the mixture of Li₃N and hexagonal boron nitride (h-BN) powders with different crystallization degrees. Using the pretreated h-BN and Li₃N, the cubic boron nitride (c-BN) was synthesized by a cubic-anvil press. According to the X-ray diffraction (XRD) data, both the crystallization degree change of the pretreated h-BN and the microstructure transition from h-BN to c-BN were analyzed. The experimental results indicated that h-BN possessing lower crystallization degree was easier to transform into c-BN.

Using in situ high-pressure synchrotron X-ray diffraction and diamond anvil cell (DAC) techniques, the phase transition and physical characteristics of B_0.47C_0.23N_0.30 compound were observed in the pressure range of 1.4~30 GPa. The experimental results showed that the B-C-N compound experiences a phase transition from hexagonal structure to wurtzite phase at 14.9 GPa. The pressure dependences of the lattice parameters and volume of wurtzite-type B-C-N were calculated. By fitting the Brich-Murnaghan equation of state to the pressure-volume data, the bulk modulus of wurtzite-type B-C-N compound was obtained as (275±26) GPa, which is very close to the value of (282±15) GPa for the cubic BC₂N.

A laser-based ultrasound system was designed and built to measure the sound velocity of mesoscale (tens of micrometer- to millimeter-sized) objects. The system uses a Q-switch laser with 6.3 ns pulse width for excitation of broadband ultrasonic waves, and an optical fiber displacement interferometer for detection. The longitudinal acoustic wave velocities of the copper foils with different thicknesses were presented, which exhibit a relatively high degree of accuracy.

Using a laser velocity interferometer system for any reflector (VISAR) and a fiber displacement interferometer (FDI), the interior ballistic projectile velocity for rifle cannon was measured. According to the interference signal obtained directly from VISAR and FDI, whose persistence time is 491 μs, the projectile velocity history ranging from 0 to 140 m/s was acquired. Therefore, the measurable displacement of projectile is 20.7 mm. In addition, the shot velocity at the muzzle was also obtained as 817 m/s. The experimental results showed that muzzle smoke is the dominant influencing factor. The research results will provide a valuable reference for the practical application of laser interferometer to interior ballistic measurement.

Based on the work of Liau et al., a one-dimensional gas-phase reaction model of laser-induced ignition of RDX was established by considering the variations of physical parameters with temperature and component concentration. Using this gas-phase reaction model and finite difference method, the ignition characteristics of RDX ignited by laser radiation of 400 W/cm² power density at 0.1 MPa and 300 K were investigated. The calculated results showed that about 90% RDX transform to gas phase by evaporation and the remaining 10% decompose in condensed phase. With the accumulation of reactant and increase of temperature, the reaction rate increases gradually and finally the gas phase is ignited at about 10 ms, which is consistent with the results reported in previous literatures.

The effects of internal chemical pressure produced by A-site ionic radius were investigated for the Ho_1-xDy_xMnO₃ system. It is found that the hexagonal HoMnO₃ is gradually transformed to orthorhombic perovskite structure as reducing A-site ion size, forming three regions which contain pure hexagonal phase, mixture of hexagonal and orthorhombic phases and pure orthorhombic phase respectively. Using Rietveld method, the crystal structures were refined, and moreover, the correlations between lattice parameters and unit cell volume as a function of Dy³⁺ ion content x were obtained. The properties of the temperature dependence of the magnetization and specific heat were also studied. It is suggested that Dy³⁺-doping would increase the ordering temperature T₂ of rare earth elements.

Using an AC impedance spectroscopy within the frequency ranges of 0.1~10⁶ Hz, the electrical conductivities of serpentinite were determined from 373 K to 933 K and at 2.0 GPa and 4.0 GPa respectively. The conduction mechanisms of serpentinite before and after dehydration were also analyzed. The experimental results show that complex impedance depends on the variation of frequency, and the electrical conductivity of serpentinite is highly dependant on temperature but only slightly on pressure. The activation enthalpies derived are ~0.6 eV before dehydration and up to 2.0 eV after dehydration. The dehydration of serpentinite, occurred at 690~761 K, causes the jump of the electrical conductivity and alters conduction mechanism. The analysis results indicate that the charge carriers in serpentinite are probably electrons transferred between Fe²⁺ and Fe³⁺ before dehydration and are dominated by ions after dehydration.