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Pearlite is a very important microstructure. Therefore, a model of the ferrite - cementite phase inter- face is constructed in this paper, and the process of nano - intrusion is simulated by molecular dynamics simulation method. By analyzing the mechanical properties and microstructure of the simulation results, the ferrite - ce- mentite phase interface effect was explored. It is found that the indenter load increases with the increase of the distance between the indenter and the grain boundary at different distances (positions of indentation) from the ferrite cementite grain boundary. When the indentation depth reaches a certain depth, the load decreases with the increasing distance. Young's modulus and maximum shear modulus are directly affected by the atomic structure below the indenter tip, and hardness is affected by both the structural integrity and type. The cementite phase interface affects the nucleation, proliferation and expansion of dislocations during the nano indentation process, and the macroscopic performance is the difference of the indenter load at different indentation positions under the same indentation depth. [ABSTRACT FROM AUTHOR]

V-5Cr-5Ti alloy is one of the main candidate structural materials for the first cladding of nuclear fusion reactor, but the theoretical research is relatively few on its mechanical properties. In this paper, the elastic constants, bulk modulus, shear modulus, Young's modulus, Poisson's ratio and Cauchy pressure of V-5Cr –5Ti alloy are calculated by using the random solid solution model and the first -principle method, and com- pared with the calculated correlation values of pure vanadium. The results show that V-5Cr-5Ti alloy has good plasticity and strength, but its plasticity is slightly lower than that of pure vanadium. The results show that the plasticity and strength of V-5Cr-5Ti alloy are reduced in varying degrees due to the addition of oxygen atom. Finally, the theoretical strengths of V –5Cr-5Ti alloy and pure vanadium are calculated, and the stress -strain diagrams of them are drawn. The above conclusion is verified again by comparison. [ABSTRACT FROM AUTHOR]

Void is a common defect in the preparation of FeCrNiCoCu high - entropy alloy. Thus, this paper employs molecular dynamic simulation to build FeCrNiCoCu models with void for uniaxial tension simulation, and explores the effect of the voids location, void radius and deformation temperature on the mechanical properties. It is found that the void in the crystal with the Z -axis orientation of [111] and at the grain-boundary(GB) will seriously reduce the yield strain and yield stress, but have little effect on the Young's modulus of the model. With the increase of the void radius at the grain boundary, in the elastic stage, the increase of the void radius increases the area of stress concentration, which is conducive to dislocation nucleation, and the mechanical proper- ties of the model decrease accordingly. In the plastic deformation stage, with the increase of the void radius, the initial dislocations tend to expand to the crystal with the Z axis orientation of [001]. The model maintains good mechanical properties at medium and low temperatures; at high temperature, the mechanical properties decrease significantly. In the high temperature plastic deformation stage, the total length of dislocation in the model is low, and the average flow stress is also low. [ABSTRACT FROM AUTHOR]

In this paper, molecular dynamics (MD) method was used to simulate the binding energy, cohesive energy density, radial distribution function and mechanical properties of the polymer bonded explosives (PBXs) systems constructed by polyurethane (Estane 5703), Ethylene - Propylene - DieneMonomer (EPDM), fluoropolymer (F2311) and 2, 6 - dipicrylamino - 3, 5 - dinitropyridine (PYX) (011 ) crystal face. The results showed that the interaction between Estane 5703 and PYX (011) is the strongest. The order of cohesive energy density between different binders and crystals is PYX/F2311 > PYX/Estane 5703 > PYX/EPDM. The radial distribution function analysis showed that the interaction between PYX (011 ) crystal face and polymer molecules is mainly electrostatic interaction. After adding three kinds of binders, the tensile strength and breaking strength of the PBX system are improved. In addition to F2311, the addition of two other binders improves the shear strain resistance of PBX system. [ABSTRACT FROM AUTHOR]

The type and position of substituents will affect the molecular structure and chemical bond strength of energetic materials, and thus affect their impact sensitivity. In this paper, the influence of amino group and methyl group on impact sensitivity of trinitrobenzene energetic materials is analyzed based on first principles. According to the calculated elastic constants, the volume modulus (B), shear modulus (G), Young's modulus (E) and Poisson's ratio (v) are obtained by Voigt-Reuss-Hill averaging method. Subsequently, the effects of the type and quantity of amino and methyl substituents on mechanical parameters, band structures, and density of states are analyzed. To a certain extent, the number of amino groups is negatively correlated with the impact sensitivity, but positively correlated with the band gap width, and the impact sensitivity of a group of amino polynitroaromatic materials can be judged by comparing the band gap values. In comparison to amino groups, the number of methyl groups displays a stronger correlation with mechanical properties and exerts a more significant influence on the total density of states. Although no direct correlation is observed between the number of methyl groups and the material's impact sensitivity, it does exhibit a negative correlation with the band gap width. Therefore, the impact sensitivity of a group of nitroaromatic energetic materials containing methyl substituents cannot be solely determined based on the magnitude of the band gap value. [ABSTRACT FROM AUTHOR]