Magnesium alloy is prone to burning during its melting and casting processes in air, which is a major factor of obstructing its application. Fluxes and cover gases are currently used for the melting and production pro...Magnesium alloy is prone to burning during its melting and casting processes in air, which is a major factor of obstructing its application. Fluxes and cover gases are currently used for the melting and production processes, and semi-solid casting is also used to shape composites made of magnesium alloy, but there still remain many problems. Alloying is a promising method of preventing magnesium from burning. The effect of RE additions on the ignition temperature of AZ91D magnesium alloy was investigated. The changes of the quality of oxidation film and the as-cast microstructure were analyzed, and the mechanical property was compared with that without rare earth. For AZ91D with RE in the range of 0.08% to 0.12%. It is shown that the ignition temperature point can be greatly heightened, the quality of oxidation film is obviously improved, the as-cast microstructure is refined greatly, and the mechanical property is bettered a little, therefore, such an alloy is promising.展开更多
The microstructure evolution and oxide film behavior in ultrasound-assisted transient liquid phase（U-TLP） bonding of Mg alloy were investigated by applying different ultrasonic time at 460？C with brass interlayer i...The microstructure evolution and oxide film behavior in ultrasound-assisted transient liquid phase（U-TLP） bonding of Mg alloy were investigated by applying different ultrasonic time at 460？C with brass interlayer in air. The results indicated that with increasing ultrasonic time, brass interlayer disappeared gradually and the Mg-Cu-Zn eutectic compounds were formed. The eutectic compounds in the joint decreased as the ultrasonic time increased further. The oxide removal process was divided into four steps. Continuous oxide film at the interface was partially fractured by ultrasonic vibration,and then suspended into liquid by undermining eutectic reaction. After that, the suspended oxide film was broken into small oxide fragments by ultrasonic cavitation effect, which was finally squeezed out of the joint by ultrasonic squeeze action. In addition, the mechanical properties of the joints were investigated. The maximum shear strength of the joint reached 105 MPa, which was 100% of base metal.展开更多
文摘Magnesium alloy is prone to burning during its melting and casting processes in air, which is a major factor of obstructing its application. Fluxes and cover gases are currently used for the melting and production processes, and semi-solid casting is also used to shape composites made of magnesium alloy, but there still remain many problems. Alloying is a promising method of preventing magnesium from burning. The effect of RE additions on the ignition temperature of AZ91D magnesium alloy was investigated. The changes of the quality of oxidation film and the as-cast microstructure were analyzed, and the mechanical property was compared with that without rare earth. For AZ91D with RE in the range of 0.08% to 0.12%. It is shown that the ignition temperature point can be greatly heightened, the quality of oxidation film is obviously improved, the as-cast microstructure is refined greatly, and the mechanical property is bettered a little, therefore, such an alloy is promising.
基金supported by the China Postdoctoral Science Foundation (No. 2015M570093)the National Natural Science Foundation of China (Grant Nos. 51520105007, 51375328)the Specialized Research Fund for Doctoral Program of Higher Education (Grant No. 20130002110009)
文摘The microstructure evolution and oxide film behavior in ultrasound-assisted transient liquid phase（U-TLP） bonding of Mg alloy were investigated by applying different ultrasonic time at 460？C with brass interlayer in air. The results indicated that with increasing ultrasonic time, brass interlayer disappeared gradually and the Mg-Cu-Zn eutectic compounds were formed. The eutectic compounds in the joint decreased as the ultrasonic time increased further. The oxide removal process was divided into four steps. Continuous oxide film at the interface was partially fractured by ultrasonic vibration,and then suspended into liquid by undermining eutectic reaction. After that, the suspended oxide film was broken into small oxide fragments by ultrasonic cavitation effect, which was finally squeezed out of the joint by ultrasonic squeeze action. In addition, the mechanical properties of the joints were investigated. The maximum shear strength of the joint reached 105 MPa, which was 100% of base metal.
