Microstructures And Properties Of Al-Li Alloys Cast By AAEC

The 3 typical kinds of Al-Li alloys,weldalite-049?2A97 and 1420 alloy,were slected as research objiects.Effects of electromagnetic conditions on the microstructures,defects,eutectics,the distribution of Cu or Mg and Li elements,macro segregation behaviors,and mechanical properties of the alloys after extrusion and heat treatments(T6and T8)was studied by optical microscope(OM),plasma emission spectrometer(ICP),scanning electron microscope(SEM),energy dispersive spectrometer analysis(EDS),electron probe micro-analyzer(EPMA)and tensile testing,based on AAEC casting(Al Alloy Mold/Ar protection Electromagnetic Casting).A new casting method——AAEC,which can cast Al-Li alloy ingots with high metallurgical quality,was developed.The main results are as followings:(1)AAEC can reduce the defect area in the surface of ingots,which improved the surface quality and increased the finished rate of ingots.(2)AAEC can significantly refine the grain zise of Al-Li alloy ingots,which resulted from that AAEC promoted the nucleation,restrained grain growth in solidification.(3)AAEC casting can improve the macrosegregation of Al-Li alloy ingots,however,intensified reverse macrosegregation in the surface of the ingots.(4)In AAEC ingots the width and area fraction of eutectics decreased,and the content of alloy elements solid solution in the matrix of Al-Li alloy ingot was signicficantly higher than that of DC ingot.(5)Above improvements in microstructures increassed the mechanical properties of aluminum lithium alloy after processing and heat treatment(T6 and T8 heat treatment).