Refractory high-entropy alloys(RHEAs)with room-temperature ductility are drawing growing attention for potential high-temperature applications.However,the most widely used metallurgical mechanisms appear weak in optim...Refractory high-entropy alloys(RHEAs)with room-temperature ductility are drawing growing attention for potential high-temperature applications.However,the most widely used metallurgical mechanisms appear weak in optimizing their strength and ductility.Here,we report that the nanoscale spinodal struc-ture in Ti_(41)V_(27)Hf_(15)Nb_(15)O_(2)leads to the highest tensile yield strength(∼1.5 GPa)among the existing RHEAs and good elongation of∼12%.With the aid of thermodynamic calculations,we show that oxygen plays a dominant role in controlling the formation of the spinodal structure by influencing the spinodal gap of the Ti-V-Hf-Nb system.Exploring the atomic structure of the spinodal structure(β+β^(∗)),we showed that the large lattice misfit of the spinodal phases is mainly responsible for the excellent strengthen-ing effect while the planar to wavy dislocation glide mode transition accounts for the retained ductility.This work provides a novel strategy to improve the mechanical properties of the RHEAs and deepens the understanding of their phase stabilities.展开更多
A defect-free Ti_(2)AlNb joint has been obtained by the inertia friction welding(IFW)technology.The weld zone(WZ)is composed of B2 grains refined by discontinuous dynamic recrystallization and enhanced by grain refine...A defect-free Ti_(2)AlNb joint has been obtained by the inertia friction welding(IFW)technology.The weld zone(WZ)is composed of B2 grains refined by discontinuous dynamic recrystallization and enhanced by grain refinement strengthening.And the average microhardness decreases by about 30 HV from the WZ to the base metal.In-situ SEM analysis reveals that the heterogeneous structure of the joint causes strong strain partitioning during tensile deformation.The microcrack initiation occurs at the interface of the initial B2 phases and B2/O boundaries.Owing to stress concentration,the multi-slip bands and cracks tend to generate in the heat-affected zone(HAZ),causing a premature fracture.展开更多
基金the financial support from the National Natural Science foundation of China(NSFC,Granted No.52001266)the Fundamental Research Funds for the Cen-tral Universities(No.G2022KY05109,No.G2022KY05113)+1 种基金Guangdong Basic and Applied Basic Research Foundation(No.2023A1515012703)The Shanghai“Phosphor”Science Foundation,China(23YF1450900)。
文摘Refractory high-entropy alloys(RHEAs)with room-temperature ductility are drawing growing attention for potential high-temperature applications.However,the most widely used metallurgical mechanisms appear weak in optimizing their strength and ductility.Here,we report that the nanoscale spinodal struc-ture in Ti_(41)V_(27)Hf_(15)Nb_(15)O_(2)leads to the highest tensile yield strength(∼1.5 GPa)among the existing RHEAs and good elongation of∼12%.With the aid of thermodynamic calculations,we show that oxygen plays a dominant role in controlling the formation of the spinodal structure by influencing the spinodal gap of the Ti-V-Hf-Nb system.Exploring the atomic structure of the spinodal structure(β+β^(∗)),we showed that the large lattice misfit of the spinodal phases is mainly responsible for the excellent strengthen-ing effect while the planar to wavy dislocation glide mode transition accounts for the retained ductility.This work provides a novel strategy to improve the mechanical properties of the RHEAs and deepens the understanding of their phase stabilities.
基金financially supported by the National Natural Science Foundation of China(No.51871183).
文摘A defect-free Ti_(2)AlNb joint has been obtained by the inertia friction welding(IFW)technology.The weld zone(WZ)is composed of B2 grains refined by discontinuous dynamic recrystallization and enhanced by grain refinement strengthening.And the average microhardness decreases by about 30 HV from the WZ to the base metal.In-situ SEM analysis reveals that the heterogeneous structure of the joint causes strong strain partitioning during tensile deformation.The microcrack initiation occurs at the interface of the initial B2 phases and B2/O boundaries.Owing to stress concentration,the multi-slip bands and cracks tend to generate in the heat-affected zone(HAZ),causing a premature fracture.
