Microstructure and hardness of twin-roll casting （TRC） process and direct-chill casting （DC） for A8006 alloy with and without homogenization were investigated by means of scanning electron microscopy （SEM）, X-ra...Microstructure and hardness of twin-roll casting （TRC） process and direct-chill casting （DC） for A8006 alloy with and without homogenization were investigated by means of scanning electron microscopy （SEM）, X-ray diffraction analysis and Vickers hardness measurement. The results show that the eutectic phase of the homogenized TRC alloy becomes fine as the microstructure of the as-cast TRC alloy is refined. The short rodlike eutectic phase of the as-cast TRC alloy is dispersed homogeneously, which is similar to the morphology of eutectic phase of the homogenized DC alloy. After homogenization, elements Fe and Mn in DC and TRC alloys are diffused from eutectic phase to A1 matrix, resulting in the decrease of microhardness. The formability of the as-cast TRC alloy is superior to that of the homogenized DC alloy. For TRC A8006 alloy, the homogenizing cycle can be removed from the subsequent processing.展开更多
Solidification behaviour of AA8006 aluminium alloy in suction casting has been investigated by field emission scanning electron microscopy with energy dispersive spectroscopy （EDS）. It is found that there is a secon...Solidification behaviour of AA8006 aluminium alloy in suction casting has been investigated by field emission scanning electron microscopy with energy dispersive spectroscopy （EDS）. It is found that there is a secondary solidification process of the remaining liquid in located region of α-Al dendrites, and the cooling rate influences not only the solidification of the primary α-Al dendrite, but also the secondary solidification process of the remaining liquid. With the primary solidification being responsible for the formation of the relatively large α- Al dendrite, a fine and homogeneous microstructure is observed in the secondary solidification. Furthermore, because of the presence of the fine microstructure, the eutectic reaction is confined into small intergranular areas, inducing the formation of the laminar eutectic phase in the primary solidification region and fibrous eutectic phase in the secondary solidification region. EDS analysis shows that the content of Fe is higher in the secondary solidification region, and the enrichment of the solute element further confirms the existence of the secondary solidification.展开更多
基金Project (42-QP-009) supported by Research Fund of the State Key Laboratory of Solidification Processing,ChinaProject (Z2012019) supported by Graduate Starting Seed Fund of Northwestern Polytechnical University,ChinaProject (B08040) supported by 111 Project
文摘Microstructure and hardness of twin-roll casting （TRC） process and direct-chill casting （DC） for A8006 alloy with and without homogenization were investigated by means of scanning electron microscopy （SEM）, X-ray diffraction analysis and Vickers hardness measurement. The results show that the eutectic phase of the homogenized TRC alloy becomes fine as the microstructure of the as-cast TRC alloy is refined. The short rodlike eutectic phase of the as-cast TRC alloy is dispersed homogeneously, which is similar to the morphology of eutectic phase of the homogenized DC alloy. After homogenization, elements Fe and Mn in DC and TRC alloys are diffused from eutectic phase to A1 matrix, resulting in the decrease of microhardness. The formability of the as-cast TRC alloy is superior to that of the homogenized DC alloy. For TRC A8006 alloy, the homogenizing cycle can be removed from the subsequent processing.
基金support from Research Fund of the State Key Laboratory of Solidification Processing (No. 42-QP-009)Fundamental Research Fund of Northwestern Polytechnical University (No. JC200929) the 111 Project (No. B08040)
文摘Solidification behaviour of AA8006 aluminium alloy in suction casting has been investigated by field emission scanning electron microscopy with energy dispersive spectroscopy （EDS）. It is found that there is a secondary solidification process of the remaining liquid in located region of α-Al dendrites, and the cooling rate influences not only the solidification of the primary α-Al dendrite, but also the secondary solidification process of the remaining liquid. With the primary solidification being responsible for the formation of the relatively large α- Al dendrite, a fine and homogeneous microstructure is observed in the secondary solidification. Furthermore, because of the presence of the fine microstructure, the eutectic reaction is confined into small intergranular areas, inducing the formation of the laminar eutectic phase in the primary solidification region and fibrous eutectic phase in the secondary solidification region. EDS analysis shows that the content of Fe is higher in the secondary solidification region, and the enrichment of the solute element further confirms the existence of the secondary solidification.
