The microstructural constituents and the crystallographic morphology of the primary intermetallic phases in permanent-mould-cast Mg-Zn-Al alloys with typical compositions within high zinc castable domain were investig...The microstructural constituents and the crystallographic morphology of the primary intermetallic phases in permanent-mould-cast Mg-Zn-Al alloys with typical compositions within high zinc castable domain were investigated. Three kinds of primary compounds with distinct morphology were identified as Mg32(Al,Zn)49(τ), MgZn(ε), and a ternary icosahedral quasi-crystalline compound (denoted with Q). The constituent is found to change with Zn and Al content and their concentration ratio. Alloys with middle mass ratio of Zn to Al and Al content, consist of α-Mg and τ phase, while alloys with high mass ratio of Zn to Al and low Al are composed of α-Mg, ε and a small amount of τ, those with low ratio of Zn to Al and high Al consist of α-Mg with Q. Solidification characteristics and process were proposed. The solidification ranges and liquidus temperature decrease with increasing Zn and Al content for τ-and Q-type alloys, whereas ε-type alloy shows reverse tendency. The second phase transformation moves to higher temperature range when Al content increases and ratio of Zn to Al decreases.展开更多
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
Alloying elements, present in the aluminum solid solution or the precipitates, influence the corrosion resistance of A1-Mg-Mn-Zn alloys. In this study, sensi- tizing treatment was applied to an A1-Mg-Mn-Zn alloy to mo...Alloying elements, present in the aluminum solid solution or the precipitates, influence the corrosion resistance of A1-Mg-Mn-Zn alloys. In this study, sensi- tizing treatment was applied to an A1-Mg-Mn-Zn alloy to modify the precipitation at the grain boundaries or in the grains. Transmission electron microscopy （TEM） and scanning electron microscope （SEM） were used to characterize various second-phase particles and determine their orientation relationship with the A1 matrix. After sensitizing treatment, z-phase （Mg32（Al, Zn）49） is observed to precipitate along the grain boundaries in a coarser size, producing a discontinuous grain boundary precipitate structure. In addition, Mn-rich particles are found to form with various shapes, such as global, plate and rhombus.展开更多
基金Project(50301018) supported by the National Natural Science Foundation of China
文摘The microstructural constituents and the crystallographic morphology of the primary intermetallic phases in permanent-mould-cast Mg-Zn-Al alloys with typical compositions within high zinc castable domain were investigated. Three kinds of primary compounds with distinct morphology were identified as Mg32(Al,Zn)49(τ), MgZn(ε), and a ternary icosahedral quasi-crystalline compound (denoted with Q). The constituent is found to change with Zn and Al content and their concentration ratio. Alloys with middle mass ratio of Zn to Al and Al content, consist of α-Mg and τ phase, while alloys with high mass ratio of Zn to Al and low Al are composed of α-Mg, ε and a small amount of τ, those with low ratio of Zn to Al and high Al consist of α-Mg with Q. Solidification characteristics and process were proposed. The solidification ranges and liquidus temperature decrease with increasing Zn and Al content for τ-and Q-type alloys, whereas ε-type alloy shows reverse tendency. The second phase transformation moves to higher temperature range when Al content increases and ratio of Zn to Al decreases.
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.
基金financially supported by the National Natural Science Foundation of China (No.51301017)the Common Construction Project from Beijing Municipal Commission of Education
文摘Alloying elements, present in the aluminum solid solution or the precipitates, influence the corrosion resistance of A1-Mg-Mn-Zn alloys. In this study, sensi- tizing treatment was applied to an A1-Mg-Mn-Zn alloy to modify the precipitation at the grain boundaries or in the grains. Transmission electron microscopy （TEM） and scanning electron microscope （SEM） were used to characterize various second-phase particles and determine their orientation relationship with the A1 matrix. After sensitizing treatment, z-phase （Mg32（Al, Zn）49） is observed to precipitate along the grain boundaries in a coarser size, producing a discontinuous grain boundary precipitate structure. In addition, Mn-rich particles are found to form with various shapes, such as global, plate and rhombus.
