In this study, compounded surface modification technology-high current pulsed electron beam （HCPEB） ＋ micro-plasma oxidation （MPO） was applied to treat ZK60 Mg alloys. The characteristics of the microstructure of...In this study, compounded surface modification technology-high current pulsed electron beam （HCPEB） ＋ micro-plasma oxidation （MPO） was applied to treat ZK60 Mg alloys. The characteristics of the microstructure of ZK60 Mg alloy after single MPO and HCPEB＋MPO compounded treatment were investigated by SEM. The results showed that the density of the ceramic layer of HCPEB＋MPO-treated ZK60 Mg alloy was improved and defects were reduced compared to that under MPO treatment alone. Surface modified layer of ZK60 Mg alloys treated by HCPEB＋MPO was divided into three zones, namely the top loose ceramic zone, middle compact zone and inside HCPEB-induced melted zone. Corrosion resistance of ZK60 Mg alloy before and after the compounded surface modification was measured in a solution of 3.5% NaCl by potentiodynamic polarization curves. It was found that the corrosion current density of ZK60 Mg alloys could be reduced by about three orders of magnitude, from 311μA/cm^2 of the original sample to 0.2μA/cm^2 of the HCPEB＋MPO-treated sample. This indicates the great application potential of the HCPEB＋MPO compounded surface modification technology in improving the corrosion resistance of ZK60 Mg alloys in the future.展开更多
Nanocrystallized Al-10.0%Zn-3.0%Mg-1.8%Cu(mass fraction)alloy powder was prepared by cryomilling,and then the nanostructured powder was consolidated into bulk material by spark plasma sintering(SPS).The microstructura...Nanocrystallized Al-10.0%Zn-3.0%Mg-1.8%Cu(mass fraction)alloy powder was prepared by cryomilling,and then the nanostructured powder was consolidated into bulk material by spark plasma sintering(SPS).The microstructural evolution and phase transformation were studied.A supersaturated face-centered cubic solid solution is formed after cryomilling for 10 h,and the average grain size is 28 nm.Two typical nanostructures of the bulk nanostructured alloy are observed:primarily equiaxed grains with size of 150 nm,and occasionally occurring sub-micron grains up to 500 nm.Two types of MgZn2 particles precipitate during consolidation. One is the sub-micron particles distributed along the boundaries of the powders,and the other is fine particles with size of several nanometers in the matrix,especially at the boundaries of sub-micron grains.These second phase particles can be completely dissolved into matrix by proper solid solution treatment.展开更多
The laser ablation-molecular beam（LA-MB） method is useful for studying the reactions of metal ions with molecular clusters. Reactions of magnesium plasma with methanol clusters were studied by using this method. A s...The laser ablation-molecular beam（LA-MB） method is useful for studying the reactions of metal ions with molecular clusters. Reactions of magnesium plasma with methanol clusters were studied by using this method. A specially designed reaction cell was used as a fast flow reactor operated under thermal conditions, and the reaction products were measured with a time-of-flight（TOF） mass spectrometer. Surprisingly, several series of cluster ions with complex sizes and intensity distributions were obtained when the laser ablating was applied to different parts of the molecular beam. In the front part of the molecular beam, strong Mg^＋ （CH3OH）n（ n = 0-5） and weak H^＋ （CH3OH）n（ n = 0-5 ） cluster ions were observed with relatively small cluster sizes ; in the middle part of the molecular beam, the main cluster ions were H^＋ （ CH3OH）n （ n = 6-17 ） and H^＋（ H2O） 2 （ CH3OH）n（ n = 6-17 ） with a relatively large cluster size and a weak intensity; in the back part of the molecular beam, two new series of cluster ions, MgO^＋ （ H2O） （ CH3 OH）n（ n = 6-10 ） and MgOCH3^＋ （ CH3OH）n（ n = 6-10）, were obtained and accompanied by weak H^＋（CH3OH）n（n = 4-7） and H^＋（ H2O）2 （CH3OH）n（ n = 3-6）. The formation mechanisms and speed characteristics of the cluster ions are discussed in this article.展开更多
Mg的吸放氢条件苛刻、动力学性能差,只有对它进行合金化,才能得到贮氢性能优异的Mg合金。本研究尝试用Cr-Mn元素对Mg进行合金化,用不同工艺方法制备Mg-Cr-Mn合金,并用X射线衍射、扫描电子显微镜和能谱仪对合金进行了物相、形貌和成分表...Mg的吸放氢条件苛刻、动力学性能差,只有对它进行合金化,才能得到贮氢性能优异的Mg合金。本研究尝试用Cr-Mn元素对Mg进行合金化,用不同工艺方法制备Mg-Cr-Mn合金,并用X射线衍射、扫描电子显微镜和能谱仪对合金进行了物相、形貌和成分表征,利用Sieverts加氢装置对部分合金进行充氢试验。研究结果表明:Mg-Cr-Mn没有形成Laves相,Mg只是少量地固溶在Cr Mn合金立方相中。Mg-Cr-Mn合金在107 k Pa、240℃下可少量吸氢。展开更多
对净化前、后合金氢含量和力学性能进行测试,并采用TEM对等离子净化后的Al-Zn-Mg合金时效组织进行分析。结果表明:Al-Zn-Mg合金氢含量由0.17 mL/100 g Al降低到0.11 mL/100 g Al;经460℃×120 min固溶、130℃×16 h时效处理后,...对净化前、后合金氢含量和力学性能进行测试,并采用TEM对等离子净化后的Al-Zn-Mg合金时效组织进行分析。结果表明:Al-Zn-Mg合金氢含量由0.17 mL/100 g Al降低到0.11 mL/100 g Al;经460℃×120 min固溶、130℃×16 h时效处理后,晶内的析出相细小弥散,晶界上析出相连续分布,GP区起主要的强化作用;Rm达到590 MPa,Rp0.2达到510 MPa,断后伸长率达到8.5%,硬度达到160HB。展开更多
基金supported by Liaoning BaiQianWan Talents Program of China (No. 2008921028)Doctoral Fund of Ministry of Education of China (No. 200801451082)
文摘In this study, compounded surface modification technology-high current pulsed electron beam （HCPEB） ＋ micro-plasma oxidation （MPO） was applied to treat ZK60 Mg alloys. The characteristics of the microstructure of ZK60 Mg alloy after single MPO and HCPEB＋MPO compounded treatment were investigated by SEM. The results showed that the density of the ceramic layer of HCPEB＋MPO-treated ZK60 Mg alloy was improved and defects were reduced compared to that under MPO treatment alone. Surface modified layer of ZK60 Mg alloys treated by HCPEB＋MPO was divided into three zones, namely the top loose ceramic zone, middle compact zone and inside HCPEB-induced melted zone. Corrosion resistance of ZK60 Mg alloy before and after the compounded surface modification was measured in a solution of 3.5% NaCl by potentiodynamic polarization curves. It was found that the corrosion current density of ZK60 Mg alloys could be reduced by about three orders of magnitude, from 311μA/cm^2 of the original sample to 0.2μA/cm^2 of the HCPEB＋MPO-treated sample. This indicates the great application potential of the HCPEB＋MPO compounded surface modification technology in improving the corrosion resistance of ZK60 Mg alloys in the future.
基金Project(2002AA302502)supported by the Hi-tech Research and Development Program of ChinaProject(20050008016)supported by the Research Fund for the Doctoral Program of Higher Education,China
文摘Nanocrystallized Al-10.0%Zn-3.0%Mg-1.8%Cu(mass fraction)alloy powder was prepared by cryomilling,and then the nanostructured powder was consolidated into bulk material by spark plasma sintering(SPS).The microstructural evolution and phase transformation were studied.A supersaturated face-centered cubic solid solution is formed after cryomilling for 10 h,and the average grain size is 28 nm.Two typical nanostructures of the bulk nanostructured alloy are observed:primarily equiaxed grains with size of 150 nm,and occasionally occurring sub-micron grains up to 500 nm.Two types of MgZn2 particles precipitate during consolidation. One is the sub-micron particles distributed along the boundaries of the powders,and the other is fine particles with size of several nanometers in the matrix,especially at the boundaries of sub-micron grains.These second phase particles can be completely dissolved into matrix by proper solid solution treatment.
基金Supported by the Doctoral Startup Foundation from Qufu Normal University.
文摘The laser ablation-molecular beam（LA-MB） method is useful for studying the reactions of metal ions with molecular clusters. Reactions of magnesium plasma with methanol clusters were studied by using this method. A specially designed reaction cell was used as a fast flow reactor operated under thermal conditions, and the reaction products were measured with a time-of-flight（TOF） mass spectrometer. Surprisingly, several series of cluster ions with complex sizes and intensity distributions were obtained when the laser ablating was applied to different parts of the molecular beam. In the front part of the molecular beam, strong Mg^＋ （CH3OH）n（ n = 0-5） and weak H^＋ （CH3OH）n（ n = 0-5 ） cluster ions were observed with relatively small cluster sizes ; in the middle part of the molecular beam, the main cluster ions were H^＋ （ CH3OH）n （ n = 6-17 ） and H^＋（ H2O） 2 （ CH3OH）n（ n = 6-17 ） with a relatively large cluster size and a weak intensity; in the back part of the molecular beam, two new series of cluster ions, MgO^＋ （ H2O） （ CH3 OH）n（ n = 6-10 ） and MgOCH3^＋ （ CH3OH）n（ n = 6-10）, were obtained and accompanied by weak H^＋（CH3OH）n（n = 4-7） and H^＋（ H2O）2 （CH3OH）n（ n = 3-6）. The formation mechanisms and speed characteristics of the cluster ions are discussed in this article.
文摘Mg的吸放氢条件苛刻、动力学性能差,只有对它进行合金化,才能得到贮氢性能优异的Mg合金。本研究尝试用Cr-Mn元素对Mg进行合金化,用不同工艺方法制备Mg-Cr-Mn合金,并用X射线衍射、扫描电子显微镜和能谱仪对合金进行了物相、形貌和成分表征,利用Sieverts加氢装置对部分合金进行充氢试验。研究结果表明:Mg-Cr-Mn没有形成Laves相,Mg只是少量地固溶在Cr Mn合金立方相中。Mg-Cr-Mn合金在107 k Pa、240℃下可少量吸氢。
