The microstructures and tensile properties of semi-solid metal high pressure die cast(SSM-HPDC) F357 alloys with low and high levels of Fe,Ni and Cr were compared in different temper conditions.ThermoCalc software was...The microstructures and tensile properties of semi-solid metal high pressure die cast(SSM-HPDC) F357 alloys with low and high levels of Fe,Ni and Cr were compared in different temper conditions.ThermoCalc software was used to predict the different intermetallics that can be expected in the alloys,and scanning electron microscopy(SEM) with energy dispersive spectroscopy(EDS) was used to investigate the actual intermetallics that formed.The influence of these intermetallics on tensile properties was quantified.The results show that lower strength is obtained in the alloy with high Fe,Ni and Cr levels.This is attributed mainly to the formation of more π-Al8FeMg3Si6 phase,which removes strengthening Mg atoms from solid solution.Also,the ductility of the high Fe,Ni and Cr levels alloy is decreased significantly due to microcracking of the higher volume fraction π-Al8FeMg3Si6 and Al9FeNi phases.The combination of lower strength and ductility results in a decrease of the quality index of this alloy compared with the alloy with low levels of Fe,Ni and Cr.展开更多
The effects of Sm additions （0, 0.5 wt.%, 1.0 wt.%and 1.5 wt.%） on the eutectic Si and β-Al5FeSi phases of ADC12 as-cast alloys were studied by optical microscopy （OM）, scanning electron microscopy （SEM） and di...The effects of Sm additions （0, 0.5 wt.%, 1.0 wt.%and 1.5 wt.%） on the eutectic Si and β-Al5FeSi phases of ADC12 as-cast alloys were studied by optical microscopy （OM）, scanning electron microscopy （SEM） and differential thermal analysis （DTA）. The experimental results showed that Sm was an effective modifying agent for the eutectic Si of ADC12 alloy, when 1.0 wt.%-1.5 wt.%Sm was added to the alloy, the coarse acicular eutectic Si was modified into fine particle or short rod structure. Moreover, the appropriate addition of Sm （about 1.0 wt.%） had marked effects on shortening the length of needle-likeβ-Al5FeSi phase. Whereas, Sm was less effective on modifying the needle-likeβ-iron to the Chinese script or sphericalα-iron phase. The modification mecha-nism was also discussed.展开更多
文摘The microstructures and tensile properties of semi-solid metal high pressure die cast(SSM-HPDC) F357 alloys with low and high levels of Fe,Ni and Cr were compared in different temper conditions.ThermoCalc software was used to predict the different intermetallics that can be expected in the alloys,and scanning electron microscopy(SEM) with energy dispersive spectroscopy(EDS) was used to investigate the actual intermetallics that formed.The influence of these intermetallics on tensile properties was quantified.The results show that lower strength is obtained in the alloy with high Fe,Ni and Cr levels.This is attributed mainly to the formation of more π-Al8FeMg3Si6 phase,which removes strengthening Mg atoms from solid solution.Also,the ductility of the high Fe,Ni and Cr levels alloy is decreased significantly due to microcracking of the higher volume fraction π-Al8FeMg3Si6 and Al9FeNi phases.The combination of lower strength and ductility results in a decrease of the quality index of this alloy compared with the alloy with low levels of Fe,Ni and Cr.
基金Project supported by National Natural Science Foundation of China(51165032,51364035)Department of Education of JiangxiProvince(GJJ13203)+2 种基金Innovative Group of Science and Technology of College of Jiangxi Province(00008713)Jiangxi Province Education Commission Foundation(GJJ13203)University-industry Cooperation Plan of Non-party Experts and Doctor of Nanchang (2012-CYH-DW-XCL-002) for financial support
文摘The effects of Sm additions （0, 0.5 wt.%, 1.0 wt.%and 1.5 wt.%） on the eutectic Si and β-Al5FeSi phases of ADC12 as-cast alloys were studied by optical microscopy （OM）, scanning electron microscopy （SEM） and differential thermal analysis （DTA）. The experimental results showed that Sm was an effective modifying agent for the eutectic Si of ADC12 alloy, when 1.0 wt.%-1.5 wt.%Sm was added to the alloy, the coarse acicular eutectic Si was modified into fine particle or short rod structure. Moreover, the appropriate addition of Sm （about 1.0 wt.%） had marked effects on shortening the length of needle-likeβ-Al5FeSi phase. Whereas, Sm was less effective on modifying the needle-likeβ-iron to the Chinese script or sphericalα-iron phase. The modification mecha-nism was also discussed.
