The commercial ZK 60 magnesium alloy with extruded state experienced aging heat treatment(T 6)was dynamically loaded at strain rate of 3000 s−1 by means of the split Hopkinson pressure bar(SHPB)in this paper.Transmiss...The commercial ZK 60 magnesium alloy with extruded state experienced aging heat treatment(T 6)was dynamically loaded at strain rate of 3000 s−1 by means of the split Hopkinson pressure bar(SHPB)in this paper.Transmission electron microscopy(TEM)observations showed that the precipitatedβ′_(1) phases partially dissolved(spheroidized)with blurred interfaces within 160μs at 3000 s^(−1).The average length and diameter of the rod-shapedβ′_(1) phase particles were 48.5 and 9.8 nm after the T 6 heat treatment;while the average diameter of the sphericalβ′_(1) phases changed to 8.8 nm after loading.The deformedβ′_(1) phase generated larger lattice distortion energy than Mg matrix under high strain rate loading.Therefore,the difference of free energy(the driving force of dissolution)between theβ′_(1) phase and the matrix increased,making the instantaneous dissolution of theβ′_(1) phase thermodynamically feasible.The dissolution(spheroidization)of theβ′_(1) phase particles was kinetically promoted because the diffusion rate of the solute Zn atoms was accelerated by combined actions of adiabatic temperature rise,high density of dislocations(vacancies)and high deviatoric stresses during high strain rate loading.The increase in hardness of ZK 60-T 6 alloy could be attributed to solid solution strengthening,dislocation strengthening and second phase particle strengthening.展开更多
基金Projects(51871243,51574290)supported by the National Natural Science Foundation of ChinaProject(ASSIKFJJ202304001)supported by the Open Fund of the National Key Laboratory of Strength and Structural Integrity,China+3 种基金Project(HT-CSNS-DG-CD-0092/2021)supported by the Guangdong-Hong Kong-Macao Joint Laboratory for Neutron Scattering Science and Technology,ChinaProject(2022KF-08)supported by the Hubei Longzhong Laboratory,ChinaProject(22kfgk06)supported by the Shock and Vibration of Engineering Materials and Structures Key Laboratory of Sichuan Province,ChinaProject(PBSKL2022C01)supported by the State Key Laboratory of Precision Blasting and Hubei Key Laboratory of Blasting Engineering,China。
文摘The commercial ZK 60 magnesium alloy with extruded state experienced aging heat treatment(T 6)was dynamically loaded at strain rate of 3000 s−1 by means of the split Hopkinson pressure bar(SHPB)in this paper.Transmission electron microscopy(TEM)observations showed that the precipitatedβ′_(1) phases partially dissolved(spheroidized)with blurred interfaces within 160μs at 3000 s^(−1).The average length and diameter of the rod-shapedβ′_(1) phase particles were 48.5 and 9.8 nm after the T 6 heat treatment;while the average diameter of the sphericalβ′_(1) phases changed to 8.8 nm after loading.The deformedβ′_(1) phase generated larger lattice distortion energy than Mg matrix under high strain rate loading.Therefore,the difference of free energy(the driving force of dissolution)between theβ′_(1) phase and the matrix increased,making the instantaneous dissolution of theβ′_(1) phase thermodynamically feasible.The dissolution(spheroidization)of theβ′_(1) phase particles was kinetically promoted because the diffusion rate of the solute Zn atoms was accelerated by combined actions of adiabatic temperature rise,high density of dislocations(vacancies)and high deviatoric stresses during high strain rate loading.The increase in hardness of ZK 60-T 6 alloy could be attributed to solid solution strengthening,dislocation strengthening and second phase particle strengthening.
