Stationary shoulder friction stir lap welding(SSFSLW) was employed to weld 2024 aluminum alloy. A coupled Eulerian-Lagrangian(CEL) model was developed to investigate the lap interface behavior during SSFSLW. Numerical...Stationary shoulder friction stir lap welding(SSFSLW) was employed to weld 2024 aluminum alloy. A coupled Eulerian-Lagrangian(CEL) model was developed to investigate the lap interface behavior during SSFSLW. Numerical results of material movement and equivalent plastic strain were in good agreement with the experimental work. With increasing welding speed, the distances from the hook tip to the top surface of the upper workpiece on the retreating side(RS) and the advancing side(AS) increase, while the distance between two wave-shaped alclads decreases. A symmetric interface bending is observed on the AS and the RS during plunging, while the interface bending on the AS is bigger than that on the RS during welding. The peak temperature of the interface on the AS is higher than that on the RS. The equivalent plastic strain gradually increases as the distance to the weld center decreases, and its peak value is obtained near the bottom of the weld.展开更多
A novel dual-rotation bobbin tool friction stir welding （DBT-FSW） was developed, in which the upper shoulder （US） and lower shoulder （LS） have different rotational speeds. This process was tried to weld 3.2 mm t...A novel dual-rotation bobbin tool friction stir welding （DBT-FSW） was developed, in which the upper shoulder （US） and lower shoulder （LS） have different rotational speeds. This process was tried to weld 3.2 mm thick alunlinum-lithium alloy sheets. The metallographic analysis and torque measurement were carried out to characterize the weld formabiliW. Experimental results show that compared to conven- tional bobbin tool friction stir welding, the DBT-FSW has an excellent process stability, and can produce the defect-free joints in a wider range of welding parameters. These can be attributed to the significant improvement of material flow caused by the formation of a staggered layer structure and the unbalanced force between the US and LS during the DBT-FSW process.展开更多
FeGa thin film has been deposited on（100）-oriented GaAs and（001）-oriented Si substrates with different film thicknesses and laser energy densities at room temperature by pulsed laser deposition system.Materials st...FeGa thin film has been deposited on（100）-oriented GaAs and（001）-oriented Si substrates with different film thicknesses and laser energy densities at room temperature by pulsed laser deposition system.Materials structure and static magnetic of FeGa film have great changes depending on the substrate and energy density of pulsed laser.X-ray diffraction reveals the presence of first-order order–disorder structure ofgrain phase and disordered bcc A2 structure on GaAs substrate.The coercivity and remanence of FeGa film on GaAs substrate ratio show a regular dependence on the thickness and energy densities.However,film on Si substrate did not exhibit structure change,which can be attributed to a large lattice mismatch between FeGa and Si.展开更多
基金supported financially by the National Natural Science Foundation of China(No.51574196)the Fund of the State Key Laboratory of Solidification Processing in NWPU(No.SKLSP201722)
文摘Stationary shoulder friction stir lap welding(SSFSLW) was employed to weld 2024 aluminum alloy. A coupled Eulerian-Lagrangian(CEL) model was developed to investigate the lap interface behavior during SSFSLW. Numerical results of material movement and equivalent plastic strain were in good agreement with the experimental work. With increasing welding speed, the distances from the hook tip to the top surface of the upper workpiece on the retreating side(RS) and the advancing side(AS) increase, while the distance between two wave-shaped alclads decreases. A symmetric interface bending is observed on the AS and the RS during plunging, while the interface bending on the AS is bigger than that on the RS during welding. The peak temperature of the interface on the AS is higher than that on the RS. The equivalent plastic strain gradually increases as the distance to the weld center decreases, and its peak value is obtained near the bottom of the weld.
基金support of the National Natural Science Foundation of China(No.51705027)the fund of the State Key Laboratory of Solidification Processing in NWPU(No.SKLSP201722)
文摘A novel dual-rotation bobbin tool friction stir welding （DBT-FSW） was developed, in which the upper shoulder （US） and lower shoulder （LS） have different rotational speeds. This process was tried to weld 3.2 mm thick alunlinum-lithium alloy sheets. The metallographic analysis and torque measurement were carried out to characterize the weld formabiliW. Experimental results show that compared to conven- tional bobbin tool friction stir welding, the DBT-FSW has an excellent process stability, and can produce the defect-free joints in a wider range of welding parameters. These can be attributed to the significant improvement of material flow caused by the formation of a staggered layer structure and the unbalanced force between the US and LS during the DBT-FSW process.
基金financially supported by the National Youth Natural Science Foundation (nos. 61601293 and 61404085)the Yangfan Plan of Shanghai Youth Science and Technology Talents (no. 15YF408800)the National Natural Science Foundation of China (nos. 11574214, 61376010)
文摘FeGa thin film has been deposited on（100）-oriented GaAs and（001）-oriented Si substrates with different film thicknesses and laser energy densities at room temperature by pulsed laser deposition system.Materials structure and static magnetic of FeGa film have great changes depending on the substrate and energy density of pulsed laser.X-ray diffraction reveals the presence of first-order order–disorder structure ofgrain phase and disordered bcc A2 structure on GaAs substrate.The coercivity and remanence of FeGa film on GaAs substrate ratio show a regular dependence on the thickness and energy densities.However,film on Si substrate did not exhibit structure change,which can be attributed to a large lattice mismatch between FeGa and Si.
