Pulsed ultrasonic field was employed in the melt of the AZ80 magnesium alloy.The effects of pulsed ultrasonic field on microstructure and mechanical properties of AZ80 magnesium alloy were investigated.The results show that the as-cast microstructure of the AZ80 alloy with pulsed ultrasonic treatment is significantly changed.Pulsed ultrasonic field significantly decreases the grain size,changes the morphologies of theβ-Mg_(17)Al_(12) phases and reduces their area fraction.It is found that pulsc width of ultrasonic plays an important role on the microstructure formation of AZ80 alloy.With increasing pulse width,grains become finer and more uniform.In the range of experimental parameters,the optimum pulse width for melt treatment process is found to be 210μs.The mechanical tests show that the mechanical properties of the as-cast AZ80 magnesium alloy with pulsed ultrasonic treatment are much higher than those of AZ80 alloy without ultrasonic field.
The effects of a low frequency electromagnetic field and a low frequency electromagnetic vibration field applied during DC casting of AZ80 Mg on microstructures and alloying element distribution in ingots were investigated.The experiments were performed both in absence and in the presence of the magnetic fields.In DC casting,the ingot exhibited coarse microstructure and severe segregation of Al.In the presence of solo low frequency alternating magnetic field,namely LFEC,the grains of the ingot was effectively refined and the segregation of Al was significantly decreased.In LFEVC,namely low frequency electromagnetic vibration casting,the ingot were significantly refined and the segregation was suppressed.With increasing the vibration intensities,the grain refinement and segregation suppression were increased.
LE Qichi,CUI Jianzhong,ZHANG Zhiqiang,and GUO Shijie Key Laboratory of EPM,Northeastern University,Shenyang 110004,China