The Fe reduction,microstructure evolution and corrosion susceptibility of Mg−Mn alloys made from magnesium scrap refining with Mn addition were investigated.The results show that significant Fe content change occurs d...The Fe reduction,microstructure evolution and corrosion susceptibility of Mg−Mn alloys made from magnesium scrap refining with Mn addition were investigated.The results show that significant Fe content change occurs during near-solid-melt treatment(NSMT)process even in the absence of Mn,because of the high saturation of Fe in the melt.Furthermore,in the NSMT process,even a small amount of Mn addition can lead to a sharp deposition of Mn atoms.The NSMT process can increase the growth rate of the Fe-rich particles,and then accelerate their sinking movement.Nevertheless,the addition of Mn hinders the coarsening process of Fe-rich particles.Besides,the corrosion susceptibility of the alloys is mainly affected by the solubility of Fe,which can be significantly reduced by Mn addition.Moreover,the presence of more Fe-rich particles does not necessarily increase the corrosion susceptibility of the alloy.Consequently,in the refining process of Mg−Mn alloys made from magnesium scrap,on the basis of NSMT process and adding an appropriate Mn content(about 0.5 wt.%),the purity of the melt can be improved,thereby obtaining an alloy with excellent corrosion resistance.展开更多
The effect of the melt holding temperature on the morphological evolution and sedimentation behavior of iron-rich intermetallics in Al-7.0 Si-1.0 Fe-1.2 Mn-0.25 Mg alloy was investigated using an optical microscope,sc...The effect of the melt holding temperature on the morphological evolution and sedimentation behavior of iron-rich intermetallics in Al-7.0 Si-1.0 Fe-1.2 Mn-0.25 Mg alloy was investigated using an optical microscope,scanning electron microscope and differential thermal analyzer.The results show that as the holding temperature decreases,the morphologies of the primary iron-rich phase in matrix change from star-like to polygonal,and the number of the primary phases gradually decreases and disappears at 615°C.Finally,the Chinese script phases with small size,high compact and uniform distribution are obtained.In contrast,the primary iron-rich phases in slag transform into a coarser polygonal shape with lower roundness,and some of them have hollow structures.Furthermore,the area fraction of intermetallics and Fe content in the matrix decrease gradually due to the formation and growth of sludge and subsequent natural sedimentation during melt holding.With the decrease of holding temperature,the main factors hindering the settlement of the primary phases are morphology,size,and density in turn.展开更多
基金Project(2016YFB0301100)supported by the National Key Research and Development Program of ChinaProject(2018CDJDCD0001)supported by the Fundamental Research Funds for the Central Universities,China。
文摘The Fe reduction,microstructure evolution and corrosion susceptibility of Mg−Mn alloys made from magnesium scrap refining with Mn addition were investigated.The results show that significant Fe content change occurs during near-solid-melt treatment(NSMT)process even in the absence of Mn,because of the high saturation of Fe in the melt.Furthermore,in the NSMT process,even a small amount of Mn addition can lead to a sharp deposition of Mn atoms.The NSMT process can increase the growth rate of the Fe-rich particles,and then accelerate their sinking movement.Nevertheless,the addition of Mn hinders the coarsening process of Fe-rich particles.Besides,the corrosion susceptibility of the alloys is mainly affected by the solubility of Fe,which can be significantly reduced by Mn addition.Moreover,the presence of more Fe-rich particles does not necessarily increase the corrosion susceptibility of the alloy.Consequently,in the refining process of Mg−Mn alloys made from magnesium scrap,on the basis of NSMT process and adding an appropriate Mn content(about 0.5 wt.%),the purity of the melt can be improved,thereby obtaining an alloy with excellent corrosion resistance.
基金Project(2017GDASCX-0117)supported by the Guangdong Academy of Sciences,ChinaProject(201806010126)supported by the Pearl River S&T Nova Program of Guangzhou,China+3 种基金Projects(2017A050503004,2017A07071029)supported by the Guangdong Provincial Program of Science and Technology,ChinaProject(18126010)supported by the Guangxi Autonomous Regional Program of Science and Technology,ChinaProject(201802030012)supported by the Guangzhou Municipal Science and Technology Bureau,ChinaProject(2017A0109005)supported by the Sihui Plan Project of Science and Technology,China.
文摘The effect of the melt holding temperature on the morphological evolution and sedimentation behavior of iron-rich intermetallics in Al-7.0 Si-1.0 Fe-1.2 Mn-0.25 Mg alloy was investigated using an optical microscope,scanning electron microscope and differential thermal analyzer.The results show that as the holding temperature decreases,the morphologies of the primary iron-rich phase in matrix change from star-like to polygonal,and the number of the primary phases gradually decreases and disappears at 615°C.Finally,the Chinese script phases with small size,high compact and uniform distribution are obtained.In contrast,the primary iron-rich phases in slag transform into a coarser polygonal shape with lower roundness,and some of them have hollow structures.Furthermore,the area fraction of intermetallics and Fe content in the matrix decrease gradually due to the formation and growth of sludge and subsequent natural sedimentation during melt holding.With the decrease of holding temperature,the main factors hindering the settlement of the primary phases are morphology,size,and density in turn.
