The effects of Zn content on the as-cast microstructure and mechanical properties of Mg-xZn-4Al alloys containing TiC and rare earth elements were investigated by optical microscopy (OM), scanning electron microscopy ...The effects of Zn content on the as-cast microstructure and mechanical properties of Mg-xZn-4Al alloys containing TiC and rare earth elements were investigated by optical microscopy (OM), scanning electron microscopy (SEM) analysis, X-ray diffraction (XRD) analysis and tensile test. The results show that Zn content which increased from 8% to 12% does not obviously influence on the alloy phase type of the Mg-xZn-4Al experimental alloys containing 0.25%RE and l%TiC, but with Zn content increasing from 8% to 12%, the amount of Mg32(Al,Zn)49 phase in the as-cast microstructure of the experimental alloys increases and its distribution becomes more continuous. In addition, the Mg-10Zn-4Al alloy containing 0.25%RE and 1TiC has the highest ultimate tensile strength at room temperature and 150℃and highest yield strength and elongation at 150℃. Furthermore, with Zn content increasing from 8% to 12%, the yield strength and elongation of Mg-xZn-4A1 experimental alloys containing 0.25%RE and 1%TiC increase and decrease at room temperature, respectively.展开更多
The oxidation behavior of TiAl-Cr(mole fraction of Cr:0-20%) was investigated at 1 173 K in air. The microstructure and composition of the oxide scale were studied by X-ray diffractometry(XRD), scanning electron micro...The oxidation behavior of TiAl-Cr(mole fraction of Cr:0-20%) was investigated at 1 173 K in air. The microstructure and composition of the oxide scale were studied by X-ray diffractometry(XRD), scanning electron microscopy(SEM) and electro-probe micro-analyses(EPMA). The results show that with the addition of Cr content from 0 to 8%, the oxidation resistance decreases, especially at 3%, which is mainly attributed to the doping effect of Cr3+. TiAl-Cr(mole fraction of Cr:15%-20%) has good oxidation resistance, and the protective alumina layer is preferentially formed on the surface of TiAl alloy, which is due to an increase of mole ratio of Al to Ti in TiAl-Cr alloys.展开更多
The corrosion and electrochemical behavior of extruded AZ31D magnesium alloys in NaCl solution were investigated using SEM, XRD and electrochemical method. It is found that AZ31D is susceptive to Cl- ion, and the open...The corrosion and electrochemical behavior of extruded AZ31D magnesium alloys in NaCl solution were investigated using SEM, XRD and electrochemical method. It is found that AZ31D is susceptive to Cl- ion, and the open circuit potential shifts to more negative values with increasing chloride concentration. Pitting occurs at corrosion potential and corrosion area enlarges with enhanced polarization. Tafel slopes of the cathode branches in different testing solution are almost the same. Cl-concentration affects cathode course slightly. High frequency capacitive loops shrink with the increase of Cl- concentration. Corrosion initiates from the grain boundary and spreads to entire surface with time.展开更多
A self-made directional solidification setup was used to prepare high purity aluminum ingots of 100mm in diameter. The morphology of the growth interface was detected by SEM and AFM, and the grain lattice orientation ...A self-made directional solidification setup was used to prepare high purity aluminum ingots of 100mm in diameter. The morphology of the growth interface was detected by SEM and AFM, and the grain lattice orientation was detected by XRD. The results indicate that the grains suffer competitive growth under any conditions in experiments. The lattice orientation of the preferred grains is determined by the flow field above the solid-liquid interface. The horizontal lattice position does not change during the growth process. However, the lattice orientation in the growth direction varies with the growth velocity and approaches to [100] gradually during the growth process.展开更多
基金Projects(2001AA331050) supported by the National High-Tech Research and Development Program of ChinaProject (CSTC-2004AA4003) supported by Chongqing Science and Technology Commission of China
文摘The effects of Zn content on the as-cast microstructure and mechanical properties of Mg-xZn-4Al alloys containing TiC and rare earth elements were investigated by optical microscopy (OM), scanning electron microscopy (SEM) analysis, X-ray diffraction (XRD) analysis and tensile test. The results show that Zn content which increased from 8% to 12% does not obviously influence on the alloy phase type of the Mg-xZn-4Al experimental alloys containing 0.25%RE and l%TiC, but with Zn content increasing from 8% to 12%, the amount of Mg32(Al,Zn)49 phase in the as-cast microstructure of the experimental alloys increases and its distribution becomes more continuous. In addition, the Mg-10Zn-4Al alloy containing 0.25%RE and 1TiC has the highest ultimate tensile strength at room temperature and 150℃and highest yield strength and elongation at 150℃. Furthermore, with Zn content increasing from 8% to 12%, the yield strength and elongation of Mg-xZn-4A1 experimental alloys containing 0.25%RE and 1%TiC increase and decrease at room temperature, respectively.
文摘The oxidation behavior of TiAl-Cr(mole fraction of Cr:0-20%) was investigated at 1 173 K in air. The microstructure and composition of the oxide scale were studied by X-ray diffractometry(XRD), scanning electron microscopy(SEM) and electro-probe micro-analyses(EPMA). The results show that with the addition of Cr content from 0 to 8%, the oxidation resistance decreases, especially at 3%, which is mainly attributed to the doping effect of Cr3+. TiAl-Cr(mole fraction of Cr:15%-20%) has good oxidation resistance, and the protective alumina layer is preferentially formed on the surface of TiAl alloy, which is due to an increase of mole ratio of Al to Ti in TiAl-Cr alloys.
基金Project (2001AA3 31050) supported by the Hi-tech Research and Development Program of China
文摘The corrosion and electrochemical behavior of extruded AZ31D magnesium alloys in NaCl solution were investigated using SEM, XRD and electrochemical method. It is found that AZ31D is susceptive to Cl- ion, and the open circuit potential shifts to more negative values with increasing chloride concentration. Pitting occurs at corrosion potential and corrosion area enlarges with enhanced polarization. Tafel slopes of the cathode branches in different testing solution are almost the same. Cl-concentration affects cathode course slightly. High frequency capacitive loops shrink with the increase of Cl- concentration. Corrosion initiates from the grain boundary and spreads to entire surface with time.
基金Project(2002AA336072) supported by the High-tech Research and Development Program of ChinaProject(03XD14009) supported by the Program of Shanghai Subject Chief Scientist
文摘A self-made directional solidification setup was used to prepare high purity aluminum ingots of 100mm in diameter. The morphology of the growth interface was detected by SEM and AFM, and the grain lattice orientation was detected by XRD. The results indicate that the grains suffer competitive growth under any conditions in experiments. The lattice orientation of the preferred grains is determined by the flow field above the solid-liquid interface. The horizontal lattice position does not change during the growth process. However, the lattice orientation in the growth direction varies with the growth velocity and approaches to [100] gradually during the growth process.
