With the experiment and finite element simulation, the influences of power ultrasonic on the solidification structure of 7050 aluminum alloy ingot in semi-continuous casting were researched, and the effects of casting...With the experiment and finite element simulation, the influences of power ultrasonic on the solidification structure of 7050 aluminum alloy ingot in semi-continuous casting were researched, and the effects of casting speed on solidification structure in ultrasonic field were also analyzed. The experiment and simulation results show that the solidification structure of the ingot is homogeneously distributed, and its grain size is obviously refined at ultrasonic power of 240 W. The average grain sizes, which can be seen from the Leica microscope, are less than 100 μm. When the casting speed is 45-50 mm/min, the best grain refinement is obtained.展开更多
The driving voltage and current signals of piezoceramic transducer (PZT) were measured directly by designing circuits from ultrasonic generator and using a data acquisition software system. The input impedance and pow...The driving voltage and current signals of piezoceramic transducer (PZT) were measured directly by designing circuits from ultrasonic generator and using a data acquisition software system. The input impedance and power of PZT were investigated by using root mean square (RMS) calculation. The vibration driven by high frequency was tested by laser Doppler vibrometer (PSV-400-M2). And the thermosonic bonding features were observed by scanning electron microscope (JSM-6360LV). The results show that the input power of bonding is lower than that of no load. The input impedance of bonding is greater than that of no load. Nonlinear phase, plastic flow and expansion period, and strengthening bonding process are shown in the impedance and power curves. The ultrasonic power is in direct proportion to the vibration displacement driven by the power, and greater displacements driven by high power (>5 W) result in welding failure phenomena, such as crack, break, and peeling off in wedge bonding. For thermosonic flip chip bonding, the high power decreases position precision of bonding or results in slippage and rotation phenomena of bumps. To improve reliability and precision of thermosonic bonding, the low ultrasonic power (about 1-5 W) should be chosen.展开更多
This study involves A356 alloy molded through ultrasonically vibrated cooling slope.The slope alongside ultrasonic power enables indispensable shear for engendering slurry from which the semisolid cast/heat treated bi...This study involves A356 alloy molded through ultrasonically vibrated cooling slope.The slope alongside ultrasonic power enables indispensable shear for engendering slurry from which the semisolid cast/heat treated billets got produced.An examination demonstrates ultrasonically vibrated cooling slope influencing the liquid fraction/microstructure/physical characteristics of stated billets.The investigation encompasses five diverse ultrasonic powers(0,75,150,200,250 W).The ultrasonic power of 150 W delivers finest/rounded microstructure with enhanced physical characteristics.Microstructural modifications reason physical transformations because of grain refinement and grain boundary/Hall-Petch strengthening.A smaller grain size reasons a higher strength/shape factor and an increased homogeneity reasons a higher ductility.Microstructural characteristics get improved by reheating.It is owing to coalescence throughout temperature homogenization.The physical characteristics is improved by reheating because of a reduced porosity and enhanced dissolution besides augmented homogeneity.A direct comparison remains impossible owing to unavailability of researches on ultrasonically vibrated cooling slope.展开更多
Effects of ultrasonic bonding parameters on atomic diffusion, microstructure at the Al-Au interface, and shear strength of Al-Au ultrasonic bonding were investigated by the combining experiments and finite element (FE...Effects of ultrasonic bonding parameters on atomic diffusion, microstructure at the Al-Au interface, and shear strength of Al-Au ultrasonic bonding were investigated by the combining experiments and finite element (FE) simulation. The quantitative model of atomic diffusion, which is related to the ultrasonic bonding parameters, time and distance, is established to calculate the atomic diffusion of the Al-Au interface. The maximum relative error between the calculated and experimental fraction of Al atom is 7.35%, indicating high prediction accuracy of this model. During the process of ultrasonic bonding, Au8Al3 is the main intermetallic compound (IMC) at the Al-Au interface. With larger bonding forces, higher ultrasonic powers and longer bonding time, it is more difficult to remove the oxide particles from the Al-Au interface, which hinders the atomic diffusion. Therefore, the complicated stress state and the existence of oxide particles both promotes the formation of holes. The shear strength of Al-Au ultrasonic bonding increases with increasing bonding force, ultrasonic power and bonding time. However, combined with the presence of holes at especial parameters, the optimal ultrasonic bonding parameter is confirmed to be a bonding force of 23 gf, ultrasonic power of 75 mW and bonding time of 21 ms.展开更多
基金Project(2010CB731700) supported by the National Basic Research Program of China
文摘With the experiment and finite element simulation, the influences of power ultrasonic on the solidification structure of 7050 aluminum alloy ingot in semi-continuous casting were researched, and the effects of casting speed on solidification structure in ultrasonic field were also analyzed. The experiment and simulation results show that the solidification structure of the ingot is homogeneously distributed, and its grain size is obviously refined at ultrasonic power of 240 W. The average grain sizes, which can be seen from the Leica microscope, are less than 100 μm. When the casting speed is 45-50 mm/min, the best grain refinement is obtained.
基金Project(50675227) supported by the National Natural Science Foundation of ChinaProject(07JJ3091) supported by Natural Science Foundation of Hunan Province, China+1 种基金Project(2007001) supported by the State Key Laboratory of Digital Manufacturing Equipment and TechnologyProject(2009CB724203) supported by the Major State Basic Research Development Program of China
文摘The driving voltage and current signals of piezoceramic transducer (PZT) were measured directly by designing circuits from ultrasonic generator and using a data acquisition software system. The input impedance and power of PZT were investigated by using root mean square (RMS) calculation. The vibration driven by high frequency was tested by laser Doppler vibrometer (PSV-400-M2). And the thermosonic bonding features were observed by scanning electron microscope (JSM-6360LV). The results show that the input power of bonding is lower than that of no load. The input impedance of bonding is greater than that of no load. Nonlinear phase, plastic flow and expansion period, and strengthening bonding process are shown in the impedance and power curves. The ultrasonic power is in direct proportion to the vibration displacement driven by the power, and greater displacements driven by high power (>5 W) result in welding failure phenomena, such as crack, break, and peeling off in wedge bonding. For thermosonic flip chip bonding, the high power decreases position precision of bonding or results in slippage and rotation phenomena of bumps. To improve reliability and precision of thermosonic bonding, the low ultrasonic power (about 1-5 W) should be chosen.
基金Project(SAP-9162)supported by the Ministry of Mines,Technology Information,Forecasting and Assessment Council(TIFAC),Department of Science and Technology(DST),India。
文摘This study involves A356 alloy molded through ultrasonically vibrated cooling slope.The slope alongside ultrasonic power enables indispensable shear for engendering slurry from which the semisolid cast/heat treated billets got produced.An examination demonstrates ultrasonically vibrated cooling slope influencing the liquid fraction/microstructure/physical characteristics of stated billets.The investigation encompasses five diverse ultrasonic powers(0,75,150,200,250 W).The ultrasonic power of 150 W delivers finest/rounded microstructure with enhanced physical characteristics.Microstructural modifications reason physical transformations because of grain refinement and grain boundary/Hall-Petch strengthening.A smaller grain size reasons a higher strength/shape factor and an increased homogeneity reasons a higher ductility.Microstructural characteristics get improved by reheating.It is owing to coalescence throughout temperature homogenization.The physical characteristics is improved by reheating because of a reduced porosity and enhanced dissolution besides augmented homogeneity.A direct comparison remains impossible owing to unavailability of researches on ultrasonically vibrated cooling slope.
基金Project(2022YFB3707201) supported by the National Key R&D Program of ChinaProject(U2341254) supported by the Ye Qisun Science Foundation of National Natural Science Foundation of China+1 种基金Projects(0604022GH0202143,0604022SH0201143) supported by the NPU Aoxiang Distinguished Young Scholars,ChinaProject supported by the Funding of Young Top-notch Talent of the National Ten Thousand Talent Program,China。
文摘Effects of ultrasonic bonding parameters on atomic diffusion, microstructure at the Al-Au interface, and shear strength of Al-Au ultrasonic bonding were investigated by the combining experiments and finite element (FE) simulation. The quantitative model of atomic diffusion, which is related to the ultrasonic bonding parameters, time and distance, is established to calculate the atomic diffusion of the Al-Au interface. The maximum relative error between the calculated and experimental fraction of Al atom is 7.35%, indicating high prediction accuracy of this model. During the process of ultrasonic bonding, Au8Al3 is the main intermetallic compound (IMC) at the Al-Au interface. With larger bonding forces, higher ultrasonic powers and longer bonding time, it is more difficult to remove the oxide particles from the Al-Au interface, which hinders the atomic diffusion. Therefore, the complicated stress state and the existence of oxide particles both promotes the formation of holes. The shear strength of Al-Au ultrasonic bonding increases with increasing bonding force, ultrasonic power and bonding time. However, combined with the presence of holes at especial parameters, the optimal ultrasonic bonding parameter is confirmed to be a bonding force of 23 gf, ultrasonic power of 75 mW and bonding time of 21 ms.
