The corrosion behavior of cast Mg-6Al-1Zn+XCa(Where X=0.5,1.0,1.5 and 2.0 wt.%Ca)magnesium alloy,aged at different temperatures of 180 ℃,200 ℃,220 ℃ and 240 ℃ was investigated in accelerated corrosion test chamber...The corrosion behavior of cast Mg-6Al-1Zn+XCa(Where X=0.5,1.0,1.5 and 2.0 wt.%Ca)magnesium alloy,aged at different temperatures of 180 ℃,200 ℃,220 ℃ and 240 ℃ was investigated in accelerated corrosion test chamber according to ASTM-B117 Standard(salt spray test).The exposed alloys were characterized by X-Ray Diffraction(XRD),Optical Microscopy(OM)and Scanning Electron Microscopy(SEM)techniques.The microstructural refinement due to calcium addition and ageing treatment results in the improvement of corrosion resistance of the experimental alloy.Corrosion rate decreases due to fine precipitation of theβ(Mg17Al12)phase distributed along theα-grain boundaries during ageing.Intermetallic phases act as a barrier,which makes the alloy more resistant to corrosion.Results found that better corrosion resistance of the alloy was observed in Mg-6Al-1Zn+1.5 wt.%Ca with 180 ℃ ageing temperature.The corrosion behavior of Mg-6Al-1Zn+XCa alloy exhibited by ASTM B117 salt spray testing and electrochemical polarization measurements showed similar trends concluding that the calcium addition and ageing temperature decreases the corrosion rate.展开更多
Mg-8Li-3Al＋xCe alloys（x = 0.5wt%, 1.0wt%, and 1.5wt%） were prepared through a casting route in an electric resistance furnace under a controlled atmosphere. The cast alloys were characterized by X-ray diffraction, ...Mg-8Li-3Al＋xCe alloys（x = 0.5wt%, 1.0wt%, and 1.5wt%） were prepared through a casting route in an electric resistance furnace under a controlled atmosphere. The cast alloys were characterized by X-ray diffraction, optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The corrosion behavior of the as-cast Mg-8Li-3Al＋xCe alloys were studied under salt spray tests in 3.5wt% NaC l solution at 35°C, in accordance with standard ASTM B-117, in conjunction with potentiodynamic polarization（PDP） tests. The results show that the addition of Ce to Mg-8Li-3Al（LA83） alloy results in the formation of Al_2Ce intermetallic phase, refines both the α-Mg phase and the Mg_（17）Al_（12） intermetallic phase, and then increases the microhardness of the alloys. The results of PDP and salt spray tests reveal that an increase in Ce content to 1.5wt% decreases the corrosion rate. The best corrosion resistance is observed for the LA83 alloy sample with 1.0wt% Ce.展开更多
文摘The corrosion behavior of cast Mg-6Al-1Zn+XCa(Where X=0.5,1.0,1.5 and 2.0 wt.%Ca)magnesium alloy,aged at different temperatures of 180 ℃,200 ℃,220 ℃ and 240 ℃ was investigated in accelerated corrosion test chamber according to ASTM-B117 Standard(salt spray test).The exposed alloys were characterized by X-Ray Diffraction(XRD),Optical Microscopy(OM)and Scanning Electron Microscopy(SEM)techniques.The microstructural refinement due to calcium addition and ageing treatment results in the improvement of corrosion resistance of the experimental alloy.Corrosion rate decreases due to fine precipitation of theβ(Mg17Al12)phase distributed along theα-grain boundaries during ageing.Intermetallic phases act as a barrier,which makes the alloy more resistant to corrosion.Results found that better corrosion resistance of the alloy was observed in Mg-6Al-1Zn+1.5 wt.%Ca with 180 ℃ ageing temperature.The corrosion behavior of Mg-6Al-1Zn+XCa alloy exhibited by ASTM B117 salt spray testing and electrochemical polarization measurements showed similar trends concluding that the calcium addition and ageing temperature decreases the corrosion rate.
文摘Mg-8Li-3Al＋xCe alloys（x = 0.5wt%, 1.0wt%, and 1.5wt%） were prepared through a casting route in an electric resistance furnace under a controlled atmosphere. The cast alloys were characterized by X-ray diffraction, optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The corrosion behavior of the as-cast Mg-8Li-3Al＋xCe alloys were studied under salt spray tests in 3.5wt% NaC l solution at 35°C, in accordance with standard ASTM B-117, in conjunction with potentiodynamic polarization（PDP） tests. The results show that the addition of Ce to Mg-8Li-3Al（LA83） alloy results in the formation of Al_2Ce intermetallic phase, refines both the α-Mg phase and the Mg_（17）Al_（12） intermetallic phase, and then increases the microhardness of the alloys. The results of PDP and salt spray tests reveal that an increase in Ce content to 1.5wt% decreases the corrosion rate. The best corrosion resistance is observed for the LA83 alloy sample with 1.0wt% Ce.
