To improve the wettability of hypereutectic Al−60Si alloy and enhance the mechanical properties of the joints,Al−60Si alloy was joined by ultrasonic soldering with Sn-9Zn solder,and a sound joint with in-situ Si parti...To improve the wettability of hypereutectic Al−60Si alloy and enhance the mechanical properties of the joints,Al−60Si alloy was joined by ultrasonic soldering with Sn-9Zn solder,and a sound joint with in-situ Si particle reinforcement was obtained.The oxide film of Al−60Si alloy at the interface was identified by transmission electron microscopy(TEM)analysis as amorphous Al_(2)O_(3).The oxide of Si particles in the base metal was also alumina.The oxide film of Al−60Si alloy was observed to be removed by ultrasonic vibration instead of holding treatment.Si particle-reinforced joints(35.7 vol.%)were obtained by increasing the ultrasonication time.The maximum shear strength peaked at 99.5 MPa for soldering at 330℃with an ultrasonic vibration time of 50 s.A model of forming of Si particles reinforced joint under the ultrasound was proposed,and ultrasonic vibration was considered to promote the dissolution of Al and migration of Si particles.展开更多
The applicability of Johnson-Mehl-Avrami(JMA)model to the crystallization kinetics of Zr60Al15Ni25 bulk amorphous alloy is investigated by differential scanning calorimetry(DSC)under isochronal and isothermal conditio...The applicability of Johnson-Mehl-Avrami(JMA)model to the crystallization kinetics of Zr60Al15Ni25 bulk amorphous alloy is investigated by differential scanning calorimetry(DSC)under isochronal and isothermal conditions.A criterion xm,at which a defined function z(x)exhibits the maximum value,is introduced to check the validity of JMA model to the kinetics analysis.The value of xm has a constant of 0.632 for JMA model.It is found that the values of xm at different isothermal annealing temperatures(743,748,753 and 758 K)are almost near 0.632,which indicates that the isothermal crystallization kinetics can be modeled by JMA equation.However,the values of xm at different heating rates(10,20,30 and 40 K/min)are about 0.52,implying that JMA model is not valid to the isochronal crystallization kinetics.The reason why the JMA model is not valid to the isochronal crystallization kinetics is discussed.展开更多
基金financial support from the National Natural Science Foundation of China(Nos.52275385,U2167216)Sichuan Province Science and Technology Support Program,China(No.2022YFG0086).
文摘To improve the wettability of hypereutectic Al−60Si alloy and enhance the mechanical properties of the joints,Al−60Si alloy was joined by ultrasonic soldering with Sn-9Zn solder,and a sound joint with in-situ Si particle reinforcement was obtained.The oxide film of Al−60Si alloy at the interface was identified by transmission electron microscopy(TEM)analysis as amorphous Al_(2)O_(3).The oxide of Si particles in the base metal was also alumina.The oxide film of Al−60Si alloy was observed to be removed by ultrasonic vibration instead of holding treatment.Si particle-reinforced joints(35.7 vol.%)were obtained by increasing the ultrasonication time.The maximum shear strength peaked at 99.5 MPa for soldering at 330℃with an ultrasonic vibration time of 50 s.A model of forming of Si particles reinforced joint under the ultrasound was proposed,and ultrasonic vibration was considered to promote the dissolution of Al and migration of Si particles.
基金Project(20051032)supported by the Natural Science Foundation of Shanxi Province,ChinaProject supported by the Shanxi Provincial Foundation for Leaders of Disciplines in Science and the Doctoral Science Foundation of Taiyuan University of Science and Technology,China
文摘The applicability of Johnson-Mehl-Avrami(JMA)model to the crystallization kinetics of Zr60Al15Ni25 bulk amorphous alloy is investigated by differential scanning calorimetry(DSC)under isochronal and isothermal conditions.A criterion xm,at which a defined function z(x)exhibits the maximum value,is introduced to check the validity of JMA model to the kinetics analysis.The value of xm has a constant of 0.632 for JMA model.It is found that the values of xm at different isothermal annealing temperatures(743,748,753 and 758 K)are almost near 0.632,which indicates that the isothermal crystallization kinetics can be modeled by JMA equation.However,the values of xm at different heating rates(10,20,30 and 40 K/min)are about 0.52,implying that JMA model is not valid to the isochronal crystallization kinetics.The reason why the JMA model is not valid to the isochronal crystallization kinetics is discussed.
