The Mg-Sn alloys,with basal or prismatic Mg_(2)Sn laths,were employed to reveal the effect of precipitate orientation on twinning behavior quantitatively.The Mg-5wt.%Sn alloys with basal or prismatic Mg_(2)Sn were com...The Mg-Sn alloys,with basal or prismatic Mg_(2)Sn laths,were employed to reveal the effect of precipitate orientation on twinning behavior quantitatively.The Mg-5wt.%Sn alloys with basal or prismatic Mg_(2)Sn were compressed to study the twinning behaviors.Subsequently,an Orowan strengthening model was developed to quantitatively investigate the critical resolved shear stress(CRSS)increment of precipitates on twinning.The results revealed that the prismatic precipitates hindered the transfer and growth of tensile twins more effectively compared with the basal precipitates.The decreased proportion of tensile twins containing prismatic Mg_(2)Sn might be attributed to a larger CRSS increment for tensile twins compared with that for basal precipitates.The obvious decreased twinning transfer in the alloy with prismatic Mg_(2)Sn could be due to its higher geometrically necessary dislocation and enhanced CRSS of tensile twins.Notably,the prismatic precipitates have a better hindering effect on tensile twins during compression.展开更多
The microstructure of the 18R-type long period stacking ordered （LPSO） phase in Mg 97 Y 2 Zn 1 alloy was investigated by the first principles calculation. The arrangement rule of Zn and Y atoms in the LPSO structure...The microstructure of the 18R-type long period stacking ordered （LPSO） phase in Mg 97 Y 2 Zn 1 alloy was investigated by the first principles calculation. The arrangement rule of Zn and Y atoms in the LPSO structure is determined theoretically. The calculation results reveal that the additive atoms are firstly located in the fault layers at the two ends of the 18R-type LPSO structure, and then extend to fault layers in the interior, which is in good agreement with the experimental observations. This feature also implies the microstructural relationship between 18R and other LPSO structures. The cohesive energy and the formation heat indicate the dependence of the stability of 18R LPSO structure on contents of Y and Zn atoms. The calculated electronic structures reveal the underlying mechanism of microstructure and the stability of 18R LPSO structure.展开更多
The effects of zirconium addition on the microstructure and mechanical properties of Mg97Y2Zn1 alloy were investigated.The microstructure of as-cast Mg97Y2Zn1 alloy is refined by the addition of zirconium.During the e...The effects of zirconium addition on the microstructure and mechanical properties of Mg97Y2Zn1 alloy were investigated.The microstructure of as-cast Mg97Y2Zn1 alloy is refined by the addition of zirconium.During the extrusion,the initial nucleation sites of the alloy are mainly original grain boundaries and secondary phase.The addition of zirconium could stimulate the DRX process because more grain boundaries are formed,which increases the dynamic recrystallization rate.Both the strength and elongation of the alloy are increased by the addition of zirconium.展开更多
The microstructure and mechanical properties of Mg94Zn2Y4 extruded alloy containing long-period stacking ordered structures were systematically investigated by SEM and TEM analyses. The results show that the 18R-LPSO ...The microstructure and mechanical properties of Mg94Zn2Y4 extruded alloy containing long-period stacking ordered structures were systematically investigated by SEM and TEM analyses. The results show that the 18R-LPSO structure and α-Mg phase are observed in cast Mg94Zn2Y4 alloy. After extrusion, the LPSO structures are delaminated and Mg-slices with width of 50-200 nm are generated. By ageing at 498 K for 36 h, the ageing peak is attained andβ′phase is precipitated. Due to this novel precipitation, the microhardness ofα-Mg matrix increases apparently from HV108.9 to HV129.7. While the microhardness for LPSO structure is stabilized at about HV145. TEM observations and SAED patterns indicate that the β′ phase has unique orientation relationships betweenα-Mg and LPSO structures, the direction in the close-packed planes ofβ′precipitates perpendicular to that ofα-Mg and LPSO structures. The ultimate tensile strength for the peak-aged alloy achieves 410.7 MPa and the significant strength originates from the coexistence ofβ′precipitates and 18R-LPSO structures.展开更多
为制备出绿色环保且耐蚀性能更好的镁合金阳极氧化膜,以无害、无污染的氢氧化钠、硅酸钠、碳酸钠和柠檬酸钠为电解液主要成分,以不同的电流密度(5~20 m A/cm^2)对Mg_(97)Y_2Zn_1-0.5Al合金进行阳极氧化,通过扫描电镜观察阳极氧化膜的表...为制备出绿色环保且耐蚀性能更好的镁合金阳极氧化膜,以无害、无污染的氢氧化钠、硅酸钠、碳酸钠和柠檬酸钠为电解液主要成分,以不同的电流密度(5~20 m A/cm^2)对Mg_(97)Y_2Zn_1-0.5Al合金进行阳极氧化,通过扫描电镜观察阳极氧化膜的表面形貌,利用动电位极化曲线和3.5%Na Cl水溶液浸泡试验检测膜层的耐腐蚀性能,研究了电流密度对膜层表面形貌与性能的影响。结果表明:恒流条件下不同电流密度时的阳极氧化过程均分为氧化膜快速生长、缓慢生长及生长相对平稳3个时期;随着电流密度的增加,氧化膜上的孔洞数目逐渐减少,孔径逐渐增大,膜层的耐蚀性能先增强后减弱;15 m A/cm^2电流密度下所得膜层的孔洞与裂纹较少,孔径较小,自腐蚀电流密度最小,腐蚀失重最小,耐蚀性最好。展开更多
基金National Natural Science Foundation of China(Nos.52004227,U22A20187,52201106)the China Postdoctoral Science Foundation(No.2020M683240)+1 种基金the Key Area Research and Development Program of Guangdong ProvinceChina(No.2020B090924002)。
文摘The Mg-Sn alloys,with basal or prismatic Mg_(2)Sn laths,were employed to reveal the effect of precipitate orientation on twinning behavior quantitatively.The Mg-5wt.%Sn alloys with basal or prismatic Mg_(2)Sn were compressed to study the twinning behaviors.Subsequently,an Orowan strengthening model was developed to quantitatively investigate the critical resolved shear stress(CRSS)increment of precipitates on twinning.The results revealed that the prismatic precipitates hindered the transfer and growth of tensile twins more effectively compared with the basal precipitates.The decreased proportion of tensile twins containing prismatic Mg_(2)Sn might be attributed to a larger CRSS increment for tensile twins compared with that for basal precipitates.The obvious decreased twinning transfer in the alloy with prismatic Mg_(2)Sn could be due to its higher geometrically necessary dislocation and enhanced CRSS of tensile twins.Notably,the prismatic precipitates have a better hindering effect on tensile twins during compression.
基金Projects(50861002,51071053)supported by the National Natural Science Foundation of ChinaProject(0991051)supported by NaturalScience Foundation of Guangxi Province,China+1 种基金Project(KF0803)supported by Open Project of Key Laboratory of Materials Design and Preparation Technology of Hunan Province,ChinaProject(X071117)supported by Scientific Research Foundation of Guangxi University,China
文摘The microstructure of the 18R-type long period stacking ordered （LPSO） phase in Mg 97 Y 2 Zn 1 alloy was investigated by the first principles calculation. The arrangement rule of Zn and Y atoms in the LPSO structure is determined theoretically. The calculation results reveal that the additive atoms are firstly located in the fault layers at the two ends of the 18R-type LPSO structure, and then extend to fault layers in the interior, which is in good agreement with the experimental observations. This feature also implies the microstructural relationship between 18R and other LPSO structures. The cohesive energy and the formation heat indicate the dependence of the stability of 18R LPSO structure on contents of Y and Zn atoms. The calculated electronic structures reveal the underlying mechanism of microstructure and the stability of 18R LPSO structure.
基金Project (51001072) supported by the National Natural Science Foundation of China
文摘The effects of zirconium addition on the microstructure and mechanical properties of Mg97Y2Zn1 alloy were investigated.The microstructure of as-cast Mg97Y2Zn1 alloy is refined by the addition of zirconium.During the extrusion,the initial nucleation sites of the alloy are mainly original grain boundaries and secondary phase.The addition of zirconium could stimulate the DRX process because more grain boundaries are formed,which increases the dynamic recrystallization rate.Both the strength and elongation of the alloy are increased by the addition of zirconium.
基金Project (BK2010392) supported by the Natural Science Foundation of Jiangsu Province of ChinaProject (3212000502) supported by the Innovation Foundation of Southeast University,China
文摘The microstructure and mechanical properties of Mg94Zn2Y4 extruded alloy containing long-period stacking ordered structures were systematically investigated by SEM and TEM analyses. The results show that the 18R-LPSO structure and α-Mg phase are observed in cast Mg94Zn2Y4 alloy. After extrusion, the LPSO structures are delaminated and Mg-slices with width of 50-200 nm are generated. By ageing at 498 K for 36 h, the ageing peak is attained andβ′phase is precipitated. Due to this novel precipitation, the microhardness ofα-Mg matrix increases apparently from HV108.9 to HV129.7. While the microhardness for LPSO structure is stabilized at about HV145. TEM observations and SAED patterns indicate that the β′ phase has unique orientation relationships betweenα-Mg and LPSO structures, the direction in the close-packed planes ofβ′precipitates perpendicular to that ofα-Mg and LPSO structures. The ultimate tensile strength for the peak-aged alloy achieves 410.7 MPa and the significant strength originates from the coexistence ofβ′precipitates and 18R-LPSO structures.
文摘为制备出绿色环保且耐蚀性能更好的镁合金阳极氧化膜,以无害、无污染的氢氧化钠、硅酸钠、碳酸钠和柠檬酸钠为电解液主要成分,以不同的电流密度(5~20 m A/cm^2)对Mg_(97)Y_2Zn_1-0.5Al合金进行阳极氧化,通过扫描电镜观察阳极氧化膜的表面形貌,利用动电位极化曲线和3.5%Na Cl水溶液浸泡试验检测膜层的耐腐蚀性能,研究了电流密度对膜层表面形貌与性能的影响。结果表明:恒流条件下不同电流密度时的阳极氧化过程均分为氧化膜快速生长、缓慢生长及生长相对平稳3个时期;随着电流密度的增加,氧化膜上的孔洞数目逐渐减少,孔径逐渐增大,膜层的耐蚀性能先增强后减弱;15 m A/cm^2电流密度下所得膜层的孔洞与裂纹较少,孔径较小,自腐蚀电流密度最小,腐蚀失重最小,耐蚀性最好。
