To clarify the mechanical behavior and deformation mechanism of rare earth magnesium(Mg)alloy WE43 under extreme service loads,high-speed impact tests under various deformation temperatures and loading paths were cond...To clarify the mechanical behavior and deformation mechanism of rare earth magnesium(Mg)alloy WE43 under extreme service loads,high-speed impact tests under various deformation temperatures and loading paths were conducted using a split Hopkinson pressure bar.The flow stress along extrusion direction(ED)and extrusion radial direction(ERD)decreases apparently with deformation temperature.Compared with conventional Mg alloys,it exhibits a slight anisotropy and an unusual C-shaped characteristic.Cellular dislocation,mechanical twin and fine grain that occur after high-speed impact deformation are insensitive to the loading direction,but strongly dependent on the deformation temperature,especially superimposed with adiabatic temperature rise.As a result,dynamic recrystallization(DRX)occurs even at an ambient temperature of 25℃.Double twinning and prismatic slip or pyramidal slip are the dominant deformation mechanisms at 25℃.These twins induce mechanical cutting refinement to form some fine-grained structures,accompanied by a small number of fine grains by twinning induced DRX.In contrast,the deformation at 250℃is mainly controlled by prismatic slip and pyramidal slip,accompanied by various types of twinning in early deformation stage.Compared with 25℃,more fine-grained microstructures are formed at 150 and 250℃through a synergy mechanism of twinning induced mechanical cutting and twinning induced DRX.展开更多
基金Project supported by the National Natural Science Foundation of China(52201074,52475344,52171115,U20A20275)the Natural Science Foundation of Hunan Province(2024JJ5644,2023JJ50109)。
文摘To clarify the mechanical behavior and deformation mechanism of rare earth magnesium(Mg)alloy WE43 under extreme service loads,high-speed impact tests under various deformation temperatures and loading paths were conducted using a split Hopkinson pressure bar.The flow stress along extrusion direction(ED)and extrusion radial direction(ERD)decreases apparently with deformation temperature.Compared with conventional Mg alloys,it exhibits a slight anisotropy and an unusual C-shaped characteristic.Cellular dislocation,mechanical twin and fine grain that occur after high-speed impact deformation are insensitive to the loading direction,but strongly dependent on the deformation temperature,especially superimposed with adiabatic temperature rise.As a result,dynamic recrystallization(DRX)occurs even at an ambient temperature of 25℃.Double twinning and prismatic slip or pyramidal slip are the dominant deformation mechanisms at 25℃.These twins induce mechanical cutting refinement to form some fine-grained structures,accompanied by a small number of fine grains by twinning induced DRX.In contrast,the deformation at 250℃is mainly controlled by prismatic slip and pyramidal slip,accompanied by various types of twinning in early deformation stage.Compared with 25℃,more fine-grained microstructures are formed at 150 and 250℃through a synergy mechanism of twinning induced mechanical cutting and twinning induced DRX.
