The new high strength, toughness and low density steel is a new generation of lightweight material with high protection, which is based on the theory of lattice dilution and lattice distortion and is manufactured by adding light elements to reduce its density. Furthermore, after impact process, the composite effects such as transformation induced plasticity (TRIP) effect, twinning induced plasticity (TWIP) effect, microbands induced plasticity (MBIP) effect and phase transformation precipitation occur in the microstructure. The specific strength and specific stiffness are better than those of aluminum, magnesium and titanium alloys, and the modulus is 3 times that of aluminum alloy and 2 times that of titanium alloy. Preliminary research shows that the application of low density steel in artillery system can greatly reduce the production cost. On the basis that all technical and tactical indexes meet the design requirements, it can realize lightweight, long-distance strategic delivery and battlefield real-time repair.

Equiatomic AlCoCrFeNi high-entropy alloy (HEA) has gained significant interest in recent years because of its excellent mechanical properties. A356 aluminum alloy reinforced by AlCoCrFeNi HEA particles was fabricated by friction stir processing (FSP) and subsequent heat treatment. Solution and aging treatments were specially performed for the composites to control the interface microstructure, and interfacial microstructure and tensile properties were explored at different conditions. The interface between the matrix and HEA particles showed a dual-layered core–shell structure and the thickness of the shell region increased with the solution time. The microstructure located in the shell layers consisted of a solid solution with increasing aluminum content, in which a radial-shaped solid solution phase formed in the region close to the core of the HEA particle and scattered solid solution grains with high Ni content formed in the region close to the matrix alloy. The gradient of composition and microstructure across the HEA/Al interface can be obtained through heat treatment, and an optimal interface bonding state and mechanical property were obtained after solution treatment for 2 h. Compared with FSPed A356 aluminum alloy, the FSPed composite enhanced the tensile stress by 60 MPa and the stain by 5% under the optimized conditions. The overgrowth of the shell layer decreased both the tensile strength and the ductile greatly due to the formation of a radial-shaped solid solution phase in the shell region.

The efficiency is affected by the parameters of components in the DC high current generator. The leakage inductance of the rectifier transformer will affect the output and filtering effect of the device and reduce the power quality of the public network. To improve the output and filtering effect of the DC high current generator, the 3-phase 6-pulsation rectifier bridge arm with the transformer T-type equivalent circuit is proposed. Through the topology model of each conduction state circuit of the semiconductor components, the expressions of load output, high-order harmonic content, and transformer leakage inductance are calculated. Then the actual generator is simulated in the MATLAB-Simulink module and variation law between the primary and secondary side leakage inductance and the output DC voltage, the total harmonic distortion(THD), and the fifth harmonic content rate is obtained. Finally, the output waveform is analyzed under the rated condition. The results show that the influence of transformer leakage inductance on output efficiency and high order harmonic filtering effect can be obtained by the proposed calculation method, and the simulation results verify the validity and correctness of the theoretical analysis.