采用光学显微镜、扫描和透射电子显微镜研究了含Ca、Si镁合金的显微组织特征。铸态下,仅含Ca的镁合金主要由镁基体和晶界离异共晶组织(Mg+Mg2Ca)组成;加入约0.5%(质量分数)Si后,晶界离异共晶组织消失,在晶界附近及晶内形成弥散分布的细...采用光学显微镜、扫描和透射电子显微镜研究了含Ca、Si镁合金的显微组织特征。铸态下,仅含Ca的镁合金主要由镁基体和晶界离异共晶组织(Mg+Mg2Ca)组成;加入约0.5%(质量分数)Si后,晶界离异共晶组织消失,在晶界附近及晶内形成弥散分布的细小点状(球状)、针状和粗块状CaMgSi相;当含Si量较高(约1.0%)时,出现中国字形(针状)的Mg2Si相。固溶时效后,只含Ca的镁合金中晶界处离异共晶组织消失,代之以长大了的颗粒状Mg2Ca相;而Mg Ca Si合金的固溶时效组织较铸态无明显变化。对合金常温和高温短时拉伸性能也作了初步探讨。展开更多
Mg alloys exhibit a number of good properties such as low density, good castability and high specific strength. However, molten Mg and Mg alloys are ignited without the melt protective gases during melting and casting...Mg alloys exhibit a number of good properties such as low density, good castability and high specific strength. However, molten Mg and Mg alloys are ignited without the melt protective gases during melting and casting process due to their high reactivity. The purpose of this study is to investigate effects of Ca and CaO on pure Mg through microstructure observation, ignition test and phase analysis. With increasing Ca and CaO contents, the ignition resistance of Ca or CaO added pure Mg is increased and the grains are refined. As results of XRD and EDS, CaO is reduced to Ca in CaO added pure Mg. Mg2Ca phase is formed even in 0.1 wt.%CaO added pure Mg by reduction mechanism, while Mg2Ca phase is formed over 1.35 wt.% Ca added pure Mg.展开更多
The single-phase Mg-4Li-0.5Ca alloy was rolled at three different temperatures(250,300 and 350℃)and followed by annealing at 200°C for 10 min.To evaluate the mechanical properties,the tensile test was conducted ...The single-phase Mg-4Li-0.5Ca alloy was rolled at three different temperatures(250,300 and 350℃)and followed by annealing at 200°C for 10 min.To evaluate the mechanical properties,the tensile test was conducted at a constant strain rate of 10^(-3)s^(-1).Factors influencing the tensile strength and strain hardening properties were assessed by microscopy,XRD and EBSD analysis.Besides,Kocks-Mecking plots(K-M)were used to determine the different stages of strain hardening exhibited by the variously processed Mg-4Li-0.5Ca alloy test specimens.The ultimate tensile strength has decreased as hot-rolling temperature in creases with increased ductility.The strain hardening properties such as hardening capacity(Hc),strain hardening exponent(n)are increased significantly with an increase in hot rolling temperature and subsequent annealing.展开更多
The microstructure of Mg-8Zn-4Al-1Ca aged alloy was investigated by TEM and HRTEM. The results show that the hardening produced in the Mg-8Zn-4Al-1Ca alloy is considerably higher than that in the Mg-8Zn-4A1 alloy. A d...The microstructure of Mg-8Zn-4Al-1Ca aged alloy was investigated by TEM and HRTEM. The results show that the hardening produced in the Mg-8Zn-4Al-1Ca alloy is considerably higher than that in the Mg-8Zn-4A1 alloy. A dense dispersion of disc-like Ca2Mg6Zn3 precipitates are formed in Mg-8Zn-4Al-1Ca alloy aged at 160 ℃ for 16 h. In addition, the lattice distortions, honeycomb-looking Moir＆#233; fringes, edge dislocations and dislocation loop also exist in the microstructure. The precipitates of alloy aged at 160 ℃ for 48 h are coarse disc-like and fine dispersed grainy. When the alloy is subjected to aging at 160 ℃ for 227 h, the microstructure consists of numerous MgZn2 precipitates and Ca2Mg6Zn3 precipitates. All the analyses show that Ca is a particularly effective trace addition in improving the age-hardening and postponing the formation of MgZn2 precipitates in Mg-8Zn-4Al alloy aged at 160 ℃.展开更多
基金Guangdong Province Key Field R&D Program Project (2020B010186002)National Natural Science Foundation of China (U2037601)Dongguan Key Technology Key Project (2019622134013)。
文摘采用光学显微镜、扫描和透射电子显微镜研究了含Ca、Si镁合金的显微组织特征。铸态下,仅含Ca的镁合金主要由镁基体和晶界离异共晶组织(Mg+Mg2Ca)组成;加入约0.5%(质量分数)Si后,晶界离异共晶组织消失,在晶界附近及晶内形成弥散分布的细小点状(球状)、针状和粗块状CaMgSi相;当含Si量较高(约1.0%)时,出现中国字形(针状)的Mg2Si相。固溶时效后,只含Ca的镁合金中晶界处离异共晶组织消失,代之以长大了的颗粒状Mg2Ca相;而Mg Ca Si合金的固溶时效组织较铸态无明显变化。对合金常温和高温短时拉伸性能也作了初步探讨。
文摘Mg alloys exhibit a number of good properties such as low density, good castability and high specific strength. However, molten Mg and Mg alloys are ignited without the melt protective gases during melting and casting process due to their high reactivity. The purpose of this study is to investigate effects of Ca and CaO on pure Mg through microstructure observation, ignition test and phase analysis. With increasing Ca and CaO contents, the ignition resistance of Ca or CaO added pure Mg is increased and the grains are refined. As results of XRD and EDS, CaO is reduced to Ca in CaO added pure Mg. Mg2Ca phase is formed even in 0.1 wt.%CaO added pure Mg by reduction mechanism, while Mg2Ca phase is formed over 1.35 wt.% Ca added pure Mg.
文摘The single-phase Mg-4Li-0.5Ca alloy was rolled at three different temperatures(250,300 and 350℃)and followed by annealing at 200°C for 10 min.To evaluate the mechanical properties,the tensile test was conducted at a constant strain rate of 10^(-3)s^(-1).Factors influencing the tensile strength and strain hardening properties were assessed by microscopy,XRD and EBSD analysis.Besides,Kocks-Mecking plots(K-M)were used to determine the different stages of strain hardening exhibited by the variously processed Mg-4Li-0.5Ca alloy test specimens.The ultimate tensile strength has decreased as hot-rolling temperature in creases with increased ductility.The strain hardening properties such as hardening capacity(Hc),strain hardening exponent(n)are increased significantly with an increase in hot rolling temperature and subsequent annealing.
基金Project(51141007)supported by the National Natural Science Foundation of ChinaProject(E2013501096)supported by Hebei Province Natural Science Foundation,China
文摘The microstructure of Mg-8Zn-4Al-1Ca aged alloy was investigated by TEM and HRTEM. The results show that the hardening produced in the Mg-8Zn-4Al-1Ca alloy is considerably higher than that in the Mg-8Zn-4A1 alloy. A dense dispersion of disc-like Ca2Mg6Zn3 precipitates are formed in Mg-8Zn-4Al-1Ca alloy aged at 160 ℃ for 16 h. In addition, the lattice distortions, honeycomb-looking Moir＆#233; fringes, edge dislocations and dislocation loop also exist in the microstructure. The precipitates of alloy aged at 160 ℃ for 48 h are coarse disc-like and fine dispersed grainy. When the alloy is subjected to aging at 160 ℃ for 227 h, the microstructure consists of numerous MgZn2 precipitates and Ca2Mg6Zn3 precipitates. All the analyses show that Ca is a particularly effective trace addition in improving the age-hardening and postponing the formation of MgZn2 precipitates in Mg-8Zn-4Al alloy aged at 160 ℃.
