The diamond growth with Fe-based catalyst at high pressure and high temperature (HPHT) was analyzed with the determinant method of ΔG<0 in thermodynamics theory, and the changes of volume with temperature and pressure were involved in the calculation. The results show that the Fe₃C phases have been formed before diamond nucleation; at the temperature and pressure range of the diamond synthesis with catalyst, the Gibbs free energies of Fe₃C⇒C (diamond) +3γ-Fe and graphite⇒diamond are all negative, but the former's absolute value is much larger than the latter's, which means the former will take place more easily. Therefore, from the viewpoint of thermodynamics the formation of Fe₃C reduces the potential energy of the transformation from graphite to diamond, and the diamond crystal growth with Fe based catalyst comes from the decomposition of Fe₃C instead of the direct transformation from graphite. Moreover, the p-T (Pressure-Temperature) equilibrium of p_eq (GPa)=1.036+0.002 36T (K) was gained, which was closer to that presented by F. P. Bundy. Thereby the thermodynamic calculation used in this paper is feasible.

Dislocation theory and molecular dynamics simulation were used to investigate the effect of atom properties on the strain-rate sensitivity of FCC metals. A method to analyze such effect is proposed. The stress dependence on dislocation velocity is identified as the key of such study and is obtained via 2-D MD simulations on the motion of an individual dislocation in FCC metals. Combining the simulation results with Orowan's relationship, it is concluded that strain rate sensitivities of FCC metals are mainly dependent on their atomic mass rather than the interatomic potential. The order of strain rate sensitivities of five FCC metals obtained by multi-scale analysis is consistent with the experimental results available.

High-pressured hydrogen's ejection caused by the structural failure of transport device could result in overpressure and mass fraction within the explosion limits. External flow field characters, hydrogen jet pressure, and mass fraction in the field were numerically simulated by using physical and calculation model in case of external flow field with or without obstacle. Hazardous area after hydrogen explosion and effect of obstacle on preventing hydrogen leakage and diffusion were obtained. The drawn conclusion could be the reference for prevention and treatment of hydrogen explosion accidents.

The high-pressure structure and isothermal equation of state of NiO were investigated up to 67 GPa by in situ synchrotron X-ray diffraction in a diamond anvil cell using argon as the pressure medium. No phase transition was found in this pressure range, nor the the pressure coefficient of axial ratio c/a became larger suddenly at about 60 GPa which was predicted by T. Sasaki. Our experiments showed that the distortion of the structure under pressure was slacker than previous results. We fit the data points to the three-order Brich-Murnaghan EOS, which resulted in a bulk modulus of B₀=195 (4) GPa with its pressure derivative B₀′=5.3 (2).

It is a new method to produce an explosively formed projectile (EFP) with fins by attaching aluminum cover on the liner. Experimental and numerical research were performed using this new method. Furthermore, the mechanism of forming fins was discussed. The new method of forming EFP with fins was simulated by LS-DYNA, and a contrastive analysis was carried out on three typical liners, including big-cone shaped, imperfect-sphere shaped and arc-cone shaped. The results from 3D numerical simulations and experiments were also analysed. Comparison of results show that three kind of liners could form obvious fins by this new method, and the results of numerical simulations are in agreement with the experiment data. The research provides a new reference method for designing EFP with fins.

SPH methods in AUTODYN-2D was used to investigate the characteristics of debris clouds propagation inside the gas-filled pressure vessels for hypervelocity impact on the pressure vessels. The effect of equation of state on debris cloud was examined. A better correlation between experimental and numerical results was obtained. The result shows a strong interaction between cloud debris and pressurized gas. The pressurized gas in vessel reduces strongly the radial and axial velocity of the debris cloud. “Spike” of the debris clouds and shock wave are shown to be important factors governing the damage of pressure vessel.

In order to study the influences of liner curvature radius on the formation of double-layer shaped charge liner (DLSCL) into tandem explosively formed projectile (EFP), the numerical simulations on the mechanical phenomenon of DLSCL forming into tandem EFP were carried out by using two-dimensional finite element dynamic code AUTODYN. The formation mechanisms of DLSCL and the influence of curvature radius on the formation of DLSCL were studied. After tests on the formation of DLSCL were performed, the X-ray pictures were obtained. Comparisons between experimental results and numerical simulation results show a good agreement. It can be concluded from the results that DLSCL can form tandem EFP and the liner curvature radius has great influence on the velocity, shape and l/D radius of tandem EFP.

Static-pressure strength, toughness index (I_T) and thermal-toughness index (I_TT) of each sample were analyzed on the basis of the experimental studies on the magnetic separation of diamond single crystal. The results show that the magnetism of synthetic diamond single crystal has an obvious influence on the mechanical performance. With the increase of magnetism, synthetic diamond single crystal becomes darker and darker in appearance color, and have more bubbles, impurities and defects inside the particles. Furthermore, their surface fineness observed under the microscope becomes worse. Meanwhile, the static-pressure strength, the I_T under the normal temperature and I_TT become lower and lower. The influence of magnetism on the static-pressure strength and the I_T is slight, however, the influence on I_TT is serious.

Based on the improved Gurney model for explosive acceleration, a planar two-stage strong detonation driving device has been optimized with genetic algorithm. The flyer and the explosive are steel and JO-9159, and the thicknesses of the first and the secondary flyer are 2.5 mm and 0.5 mm, respectively. The maximal velocity of the secondary flyer and the optimized thickness of the explosive are obtained at different velocities of the first flyer from 5.0 km/s to 6.5 km/s. In a similar way, the optimized parameters are also obtained when the flyer's material is aluminium, copper, molybdenum and tantalum, respectively, with a initial velocity of the first flyer of 5.0 km/s. The calculation results can be used in experimental design of planar two-stage strong detonation driving device.

La-filled skutterudite compounds La_xCo₄Sb₁₂ (0<x≤1.0) were successfully synthesized at 3.5 GPa and 900 K. The X-ray diffraction results indicate that all synthesized samples exist as a single phase with a crystal structure of CoSb₃. The composition-dependent electric transport properties of La-filled CoSb₃ have been studied at room temperature. The lattice parameters of the samples increase gradually with the increasing of La content. No La phase is found in the range of x from 0.1 to 1.0. The La-filled skutterudite is p type semiconductor. The electrical resistivity and Seebeck coefficient increase firstly with the increasing of La content and then decrease. When the La content x is 0.3, the electrical resistivity and Seebeck coefficient both reach the maximum value. The maximum power factor is obtained when the La content x is 0.5.