In this study, a stand-off and collinear double pulse laser-induced breakdown spectroscopy （DP LIBS） system was designed, and the magnesium alloy samples at a distance of 2.5 m away from the LIBS system were measure...In this study, a stand-off and collinear double pulse laser-induced breakdown spectroscopy （DP LIBS） system was designed, and the magnesium alloy samples at a distance of 2.5 m away from the LIBS system were measured. The effect of inter-pulse delay on spectra was studied, and the signal enhancement was observed compared to the single pulse LIBS （SP LIBS）. The morphology of the ablated crater on the sample indicated a higher efficiency of surface pretreatment in DP LIBS. The calibration curves of Ytterbium （Y） and Zirconium （Zr） were investigated. The square of the correlation coefficient of the calibration curve of element Y reached up to 0.9998.展开更多
In repair of aircraft structures of magnesium alloy ML10,the argon arc non-consumable electrode welding is used.In this case,the residual welding stresses occur in repairwelds,being one of the causes for reducing the ...In repair of aircraft structures of magnesium alloy ML10,the argon arc non-consumable electrode welding is used.In this case,the residual welding stresses occur in repairwelds,being one of the causes for reducing the service characteristics of the restored products.Residual stresses arise as a result of welding.Post-weld heat treatment is used to reduce the residual stresses.The heat treatment,which occurs after welding,increases the cost of repair.This leads to the search for alternative methods to control the stressed state of welded joints,one of which is electrodynamic treatment,which reduces the level of residual stresses in repair welds,and as a consequence,the cost of the welding repair in restoring aircraft structures.It was found from the results of experiments carried out,that the electrodynamic treatment allows reduces the initial level of stresses in welded joints,reaching 120 MPa,to 30 MPa,and at definite geometric characteristics of the specimens forming the field of compressive stresses,the values ofwhich are equal to-50 MPa.It is shown that the optimum distance between the zones of treatment,being 5 mm,provides the guaranteed covering the zones of electrodynamic effect and,as a consequence,the maximum efficiency of the electric dynamic treatment.展开更多
This study aims to investigate the promotion effect of twinning-induced nucleation vs the inhibition effect of Mgi7Ali2 particles pinning for recrystallization, achieved through gradient rolling for Mg-3Al-lZn (AZ31) ...This study aims to investigate the promotion effect of twinning-induced nucleation vs the inhibition effect of Mgi7Ali2 particles pinning for recrystallization, achieved through gradient rolling for Mg-3Al-lZn (AZ31) and Mg-9Al-lZn (AZ91) alloys as well as pure Mg. Through gradient rolling, a transition zone from the initial to deformed microstructure undergoing varying thickness reductions was obtained in the same sample, where the evolution of deformation twins and second phase can be examined precisely and continuously. During hot deformation, dynamic recrystallized (DRXed) grains tended to originate from {10 T 1 }-{10 T 2} double twins, whose nucleation was significantly restricted by increasing A1 content and hence recrystallization can be rarely triggered in AZ91 alloy. Concurrently, the size and volume fraction of Mgi7Ali2 particles changed via dissolution and re-precipitation, leading to finer average size and higher volume fraction, which produced stronger pinning effect and hindered dynamic recrystallization significantly. The current study provides insights into the mechanisms responsible for dynamic recrystallization behavior during hot rolling in Mg-AI-Zn alloys.展开更多
基金supported by National Natural Science Foundation of China(No.61473279)the National High-Tech Research and Development Program of China(863 Program)(No.2012AA040608)Equipment Development Programs of the Chinese Academy of Sciences(No.YZ201247)
文摘In this study, a stand-off and collinear double pulse laser-induced breakdown spectroscopy （DP LIBS） system was designed, and the magnesium alloy samples at a distance of 2.5 m away from the LIBS system were measured. The effect of inter-pulse delay on spectra was studied, and the signal enhancement was observed compared to the single pulse LIBS （SP LIBS）. The morphology of the ablated crater on the sample indicated a higher efficiency of surface pretreatment in DP LIBS. The calibration curves of Ytterbium （Y） and Zirconium （Zr） were investigated. The square of the correlation coefficient of the calibration curve of element Y reached up to 0.9998.
文摘In repair of aircraft structures of magnesium alloy ML10,the argon arc non-consumable electrode welding is used.In this case,the residual welding stresses occur in repairwelds,being one of the causes for reducing the service characteristics of the restored products.Residual stresses arise as a result of welding.Post-weld heat treatment is used to reduce the residual stresses.The heat treatment,which occurs after welding,increases the cost of repair.This leads to the search for alternative methods to control the stressed state of welded joints,one of which is electrodynamic treatment,which reduces the level of residual stresses in repair welds,and as a consequence,the cost of the welding repair in restoring aircraft structures.It was found from the results of experiments carried out,that the electrodynamic treatment allows reduces the initial level of stresses in welded joints,reaching 120 MPa,to 30 MPa,and at definite geometric characteristics of the specimens forming the field of compressive stresses,the values ofwhich are equal to-50 MPa.It is shown that the optimum distance between the zones of treatment,being 5 mm,provides the guaranteed covering the zones of electrodynamic effect and,as a consequence,the maximum efficiency of the electric dynamic treatment.
基金financially supported by the National Key Research and Development Program (Nos. 2017YFA0403700 and 2016YFE0115300)the National Natural Science Foundation of China (Nos. 51671093, 51625402, and 51790483)Partial financial support came from The Changjiang Scholars Program (No. T2017035)
文摘This study aims to investigate the promotion effect of twinning-induced nucleation vs the inhibition effect of Mgi7Ali2 particles pinning for recrystallization, achieved through gradient rolling for Mg-3Al-lZn (AZ31) and Mg-9Al-lZn (AZ91) alloys as well as pure Mg. Through gradient rolling, a transition zone from the initial to deformed microstructure undergoing varying thickness reductions was obtained in the same sample, where the evolution of deformation twins and second phase can be examined precisely and continuously. During hot deformation, dynamic recrystallized (DRXed) grains tended to originate from {10 T 1 }-{10 T 2} double twins, whose nucleation was significantly restricted by increasing A1 content and hence recrystallization can be rarely triggered in AZ91 alloy. Concurrently, the size and volume fraction of Mgi7Ali2 particles changed via dissolution and re-precipitation, leading to finer average size and higher volume fraction, which produced stronger pinning effect and hindered dynamic recrystallization significantly. The current study provides insights into the mechanisms responsible for dynamic recrystallization behavior during hot rolling in Mg-AI-Zn alloys.
