As-cast beryllium-aluminum(Be-Al)alloy exhibits a coarse microstructure with pore defects due to a large solidification interval,greatly limiting its mechanical properties.In this research,the relationship between las...As-cast beryllium-aluminum(Be-Al)alloy exhibits a coarse microstructure with pore defects due to a large solidification interval,greatly limiting its mechanical properties.In this research,the relationship between laser surface remelting process and microstructure and hardness of as-cast Be-Al-Sc-Zr alloy was established.The experimental results demonstrated that a pore-free refined microstructure of remelted layer was obtained by controlling the parameter of effective laser energy input.The microstructure of as-cast Be-Al-Sc-Zr alloy consisted of equiaxed grains with Al phase forming a continuous frame wrapping Be phase,which was significantly refined in the remelted zone(from 25μm to 2μm).The Vickers hardness in the remelted zone(approximately 210 HV)was approximately 3 times that of as-cast Be-Al-Sc-Zr alloy.Analysis of the Vickers hardness and the Be phase size showed a good agreement with a Hall-Petch equation.In addition,transmission electron microscopy(TEM),auger electron spectroscopy(AES)and X-ray diffraction(XRD)analysis evidenced that Sc and Zr elements formed a single blocky phase Be13(Scx,Zr1-x),which was also greatly refined from 8μm to 1.5μm in the remelted zone.The results obtained in this study indicate that the laser surface remelting allowed refining the microstructure and further strengthening the Vickers hardness of Be-Al-Sc-Zr alloy.展开更多
The effects of Ag,Co,and Ge additions on microstructure and mechanical properties of Be-35Al(wt.%)alloys fabricated by investment casting were studied.The results reveal that the trace metals 1.5wt.%Ag,0.7wt.%Co,and 0...The effects of Ag,Co,and Ge additions on microstructure and mechanical properties of Be-35Al(wt.%)alloys fabricated by investment casting were studied.The results reveal that the trace metals 1.5wt.%Ag,0.7wt.%Co,and 0.8wt.%Ge additions do not change the nucleation temperature of Be phase.However,the nucleation temperature of the Al phase decreases from 642℃ to 630℃ by DSC due to the Ge addition.The strength of the alloys sharply increases due to the dissolution of the Ag and Ge solutes into the Al phase and the Co into the Be phase characterized by SEM and EDS.Obviously,the strength of Be-Al-Ag-Co-Ge alloy is improved by the solution strengthening.Furthermore,a few Ag_(3) Al particles contribute to the strength of the Al phase.Be-Fe-Al ternary intermetallic compounds which can effectively reduce the negative effect of an impurity element Fe on the mechanical properties of Be-Al alloys are also found by XRD and EDS.展开更多
基金co-supported by the National Key Technologies R&D Program of China(No.2016YFB0700404)。
文摘As-cast beryllium-aluminum(Be-Al)alloy exhibits a coarse microstructure with pore defects due to a large solidification interval,greatly limiting its mechanical properties.In this research,the relationship between laser surface remelting process and microstructure and hardness of as-cast Be-Al-Sc-Zr alloy was established.The experimental results demonstrated that a pore-free refined microstructure of remelted layer was obtained by controlling the parameter of effective laser energy input.The microstructure of as-cast Be-Al-Sc-Zr alloy consisted of equiaxed grains with Al phase forming a continuous frame wrapping Be phase,which was significantly refined in the remelted zone(from 25μm to 2μm).The Vickers hardness in the remelted zone(approximately 210 HV)was approximately 3 times that of as-cast Be-Al-Sc-Zr alloy.Analysis of the Vickers hardness and the Be phase size showed a good agreement with a Hall-Petch equation.In addition,transmission electron microscopy(TEM),auger electron spectroscopy(AES)and X-ray diffraction(XRD)analysis evidenced that Sc and Zr elements formed a single blocky phase Be13(Scx,Zr1-x),which was also greatly refined from 8μm to 1.5μm in the remelted zone.The results obtained in this study indicate that the laser surface remelting allowed refining the microstructure and further strengthening the Vickers hardness of Be-Al-Sc-Zr alloy.
基金supported by the State Key Laboratory of Special Rare Metal Materials (Contract No. SKL2018K004)China Nonferrous Metal Mining (Group) Co.,Ltd.,Science and Technology Planning Projects (2018KJJH02, 2020KJJH04)+1 种基金the Central Government Directs Special Projects for the Development of Local Science and Technology (2020)Ningxia Hui Autonomous Region Industrial Innovation List Unwrapping Project (20200108)
文摘The effects of Ag,Co,and Ge additions on microstructure and mechanical properties of Be-35Al(wt.%)alloys fabricated by investment casting were studied.The results reveal that the trace metals 1.5wt.%Ag,0.7wt.%Co,and 0.8wt.%Ge additions do not change the nucleation temperature of Be phase.However,the nucleation temperature of the Al phase decreases from 642℃ to 630℃ by DSC due to the Ge addition.The strength of the alloys sharply increases due to the dissolution of the Ag and Ge solutes into the Al phase and the Co into the Be phase characterized by SEM and EDS.Obviously,the strength of Be-Al-Ag-Co-Ge alloy is improved by the solution strengthening.Furthermore,a few Ag_(3) Al particles contribute to the strength of the Al phase.Be-Fe-Al ternary intermetallic compounds which can effectively reduce the negative effect of an impurity element Fe on the mechanical properties of Be-Al alloys are also found by XRD and EDS.
