The effect of precipitation on the internal friction(IF)of AZ91 magnesium alloy was investigated by using X-ray diffraction(XRD)analysis,scanning electron microscope(SEM)observation,and dynamic mechanical analysis(DMA...The effect of precipitation on the internal friction(IF)of AZ91 magnesium alloy was investigated by using X-ray diffraction(XRD)analysis,scanning electron microscope(SEM)observation,and dynamic mechanical analysis(DMA).Six different states of alloy were prepared by applying different heat treatment processes:as-cast,in-complete solid solution,complete solid solution,micro-precipitation,continuous precipitation and continuous-discontinuous precipitation.It was found that the internal friction of in-completely solid-solutionized,completely solid-solutionized and micro-precipitated specimens showed a similar characteristic,and the grain boundary relaxation is completed depressed due to the Al atoms supersaturated in theα-Mg solution.However,a thermal relaxation internal friction peak was observed for continuously precipitated and continuously-discontinuously precipitated specimens at around 438 K and frequency of about 1 Hz,which was attributed to the grain boundaries relaxation.Furthermore,it was found that the relaxation of theβ-Mg17Al12/α-Mg phase interfaces should give its contribution to the background internal friction in the as-cast,continuously precipitated and continuously-discontinuously precipitated specimens.展开更多
The recent progress and future prospects for ultra-centrifugal sedimentation in solids are described,mainly involving equipment,miscible systems and compounds.Almost 90%ultracentrifugation experiments were performed o...The recent progress and future prospects for ultra-centrifugal sedimentation in solids are described,mainly involving equipment,miscible systems and compounds.Almost 90%ultracentrifugation experiments were performed on the 1st and 2nd high-temperature ultracentrifuge which is typically operated at temperatures below 500℃ under the maximum centrifugal acceleration up to 106 g.The strong gravitational and temperature fields induce atomic-scale graded structure,grain growth and refinement,and voids accumulation caused by the atomic sedimentation in miscible systems.New structures,properties and substances are produced in some compounds.A new cantilever high-temperature ultracentrifuge with a test temperature up to 1200℃ is under construction at Zhejiang University,making it possible to simulate the composition,microstructure and property evolution of superalloys in the operating environment of aircraft engines.展开更多
文摘The effect of precipitation on the internal friction(IF)of AZ91 magnesium alloy was investigated by using X-ray diffraction(XRD)analysis,scanning electron microscope(SEM)observation,and dynamic mechanical analysis(DMA).Six different states of alloy were prepared by applying different heat treatment processes:as-cast,in-complete solid solution,complete solid solution,micro-precipitation,continuous precipitation and continuous-discontinuous precipitation.It was found that the internal friction of in-completely solid-solutionized,completely solid-solutionized and micro-precipitated specimens showed a similar characteristic,and the grain boundary relaxation is completed depressed due to the Al atoms supersaturated in theα-Mg solution.However,a thermal relaxation internal friction peak was observed for continuously precipitated and continuously-discontinuously precipitated specimens at around 438 K and frequency of about 1 Hz,which was attributed to the grain boundaries relaxation.Furthermore,it was found that the relaxation of theβ-Mg17Al12/α-Mg phase interfaces should give its contribution to the background internal friction in the as-cast,continuously precipitated and continuously-discontinuously precipitated specimens.
基金National Natural Science Foundation of China(51988101)Fundamental Research Funds for the Central Universities(226-2022-00050)。
文摘The recent progress and future prospects for ultra-centrifugal sedimentation in solids are described,mainly involving equipment,miscible systems and compounds.Almost 90%ultracentrifugation experiments were performed on the 1st and 2nd high-temperature ultracentrifuge which is typically operated at temperatures below 500℃ under the maximum centrifugal acceleration up to 106 g.The strong gravitational and temperature fields induce atomic-scale graded structure,grain growth and refinement,and voids accumulation caused by the atomic sedimentation in miscible systems.New structures,properties and substances are produced in some compounds.A new cantilever high-temperature ultracentrifuge with a test temperature up to 1200℃ is under construction at Zhejiang University,making it possible to simulate the composition,microstructure and property evolution of superalloys in the operating environment of aircraft engines.
