The age-hardening response and related precipitate microstructure in Mg-Pb alloys with different Zn contents have been examined systematically.The agehardening response significantly improves with increasing Zn conten...The age-hardening response and related precipitate microstructure in Mg-Pb alloys with different Zn contents have been examined systematically.The agehardening response significantly improves with increasing Zn content.Specifically,the addition of 3 wt%Zn results in a twofold increase in hardness increment,from 9.7 to 21.3HV,during ageing at 160℃.The precipitation kinetics is also facilitated,leading to a shorter time to reach peak hardness from 3000 to 200 h.The enhanced age-hardening response is attributed to the threefold increase in the number density ofγ-Mg_(2)Pb precipitates and the uniform contribution of rod-like Zn-rich precipitates in the Mg-PbZn alloy.In the Zn-free alloy,y precipitates typically have a basal lath-like morphology,whereas in the Mg-Pb-Zn alloy,prismatic and pyramidal y lath precipitates are also frequently observed,leading to the formation of two types of novel orientation relationships.Zn solute atom segregation is detected at theγprecipitate/matrix interface,which slows the coarsening rate,refines precipitate size,and hence increases the number density of y precipitates by a factor of three in the Mg-Pb-Zn alloy.Additionally,each y precipitate always contacts with a rod-like precipitate in the peak-aged samples.Micro structure characterization performed at the early stage of ageing suggests that rodlike Zn-rich precipitates act as abundant heterogeneous nucleation sites for y-Mg_(2)Pb precipitates,which should be another reason for the refinement of y precipitate in the Zncontaining alloys.These results provide new insights into the development of novel precipitation-hardenable Mg alloys via micro-alloying elements.展开更多
The effect of vanadium nitride(VN)particles additives on microstructure and mechanical properties of the extruded AZ31 Mg alloy was systematically investigated.The experimental results revealed that the addition of 0....The effect of vanadium nitride(VN)particles additives on microstructure and mechanical properties of the extruded AZ31 Mg alloy was systematically investigated.The experimental results revealed that the addition of 0.5 wt%VN decreased the average grain size of AZ31 Mg alloy from 6.4 to 4.9µm.With the increase in VN content,the refining effect would weaken because excessive VN particles would negatively affect the dynamic recrystallization process of the alloys.The scanning electron microscopy and energy-dispersive spectroscopy indicated that AlN,VN and Al-V-N particles with different morphologies were distributed in the streamline along the extrusion direction during the extrusion process.The mechanical properties of AZ31 Mg alloy vary with the addition of VN.The extruded AZ31+0.5 wt%VN Mg alloy possesses an excellent combination of high strength and ductility.The yield strength and ultimate tensile strength of the extruded AZ31+0.5 wt%VN Mg alloy were increased without sacrificing ductility.This is mainly due to the grain refinement caused by double-heterogeneous nucleation particles.With a further increase in VN content,the presence of excessive VN particles increases the stress concentration,and the initiation source of microcracks in the alloy during alloy deformation makes the cracks more easily propagated and results in a decrease in the ductility of the extruded alloy.展开更多
基金financially supported by National Key R&D Program of China(No.2023YFB3710901)the National Natural Science Foundation of China(Nos.U22A20187,52401147,52071033 and 52471131)+3 种基金the Natural Science Foundation of Hunan Province(No.2025JJ60276)Natural Science Foundation of Jiangsu Province(No.BK20240353)the Fund of State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle(Nos.72475011 and 734215242)the Fundamental Research Funds for the Central Universities(No.2024CDJXY003)
文摘The age-hardening response and related precipitate microstructure in Mg-Pb alloys with different Zn contents have been examined systematically.The agehardening response significantly improves with increasing Zn content.Specifically,the addition of 3 wt%Zn results in a twofold increase in hardness increment,from 9.7 to 21.3HV,during ageing at 160℃.The precipitation kinetics is also facilitated,leading to a shorter time to reach peak hardness from 3000 to 200 h.The enhanced age-hardening response is attributed to the threefold increase in the number density ofγ-Mg_(2)Pb precipitates and the uniform contribution of rod-like Zn-rich precipitates in the Mg-PbZn alloy.In the Zn-free alloy,y precipitates typically have a basal lath-like morphology,whereas in the Mg-Pb-Zn alloy,prismatic and pyramidal y lath precipitates are also frequently observed,leading to the formation of two types of novel orientation relationships.Zn solute atom segregation is detected at theγprecipitate/matrix interface,which slows the coarsening rate,refines precipitate size,and hence increases the number density of y precipitates by a factor of three in the Mg-Pb-Zn alloy.Additionally,each y precipitate always contacts with a rod-like precipitate in the peak-aged samples.Micro structure characterization performed at the early stage of ageing suggests that rodlike Zn-rich precipitates act as abundant heterogeneous nucleation sites for y-Mg_(2)Pb precipitates,which should be another reason for the refinement of y precipitate in the Zncontaining alloys.These results provide new insights into the development of novel precipitation-hardenable Mg alloys via micro-alloying elements.
基金supports from the National Natural Science Foundation of China(Nos.52171099,52105140,and 51301025)the Natural Science Foundation of Hunan Province(No.2021JJ40583)+1 种基金the Natural Science Foundation of Changsha City(No.kq2014096)the Open Research Fund of Science and Technology Innovation Platform of Key Laboratory of Efficient&Clean Energy Utilization,and the Education Department of Hunan Province(No.2018NGQ004).
文摘The effect of vanadium nitride(VN)particles additives on microstructure and mechanical properties of the extruded AZ31 Mg alloy was systematically investigated.The experimental results revealed that the addition of 0.5 wt%VN decreased the average grain size of AZ31 Mg alloy from 6.4 to 4.9µm.With the increase in VN content,the refining effect would weaken because excessive VN particles would negatively affect the dynamic recrystallization process of the alloys.The scanning electron microscopy and energy-dispersive spectroscopy indicated that AlN,VN and Al-V-N particles with different morphologies were distributed in the streamline along the extrusion direction during the extrusion process.The mechanical properties of AZ31 Mg alloy vary with the addition of VN.The extruded AZ31+0.5 wt%VN Mg alloy possesses an excellent combination of high strength and ductility.The yield strength and ultimate tensile strength of the extruded AZ31+0.5 wt%VN Mg alloy were increased without sacrificing ductility.This is mainly due to the grain refinement caused by double-heterogeneous nucleation particles.With a further increase in VN content,the presence of excessive VN particles increases the stress concentration,and the initiation source of microcracks in the alloy during alloy deformation makes the cracks more easily propagated and results in a decrease in the ductility of the extruded alloy.
