In dry storage,spent fuel is typically stored in casks constructed from neutron absorbing materials(NAMs).The(B_(4)C+Al_(2)O_(3))/Al composite,which incorporates in-situ amorphous Al_(2)O_(3)(am-Al_(2)O_(3))formed on ...In dry storage,spent fuel is typically stored in casks constructed from neutron absorbing materials(NAMs).The(B_(4)C+Al_(2)O_(3))/Al composite,which incorporates in-situ amorphous Al_(2)O_(3)(am-Al_(2)O_(3))formed on fine aluminum powder as a reinforcing phase,can serve as an integrated structural and functional NAM for dry storage applications.Welding is crucial in the fabrication of these casks.In this study,friction stir welding was performed on(B_(4)C+Al_(2)O_(3))/Al composite sheets at a welding speed of 50 mm/min and rotation rates ranging from 500 to 1000 r/min.The microstructure of the weld joints was analyzed,and the intrinsic relationship between fracture behavior and microstructure was elucidated.Results showed that defect-free joints were achieved at rotation rates of 500 and 750 r/min,while tunnel defects were observed at 1000 r/min.The ultimate tensile strength of the joint welded at 500 r/min was 205.7 MPa,with a strength efficiency of 82%.Microstructural analysis revealed that the grains within the nugget zones(NZs)coarsened and the Al_(2)O_(3)network was disrupted due to the welding thermo-mechanical effect,resulting in softening within the NZs.Fracture locations for all three joints were consistently observed at the NZ boundary on the advancing side(AS).Finite element simulations confirmed that cracks propagated along the NZ boundary on the AS,where stress concentration occurred during tensile testing.展开更多
B_(4)C/Al composites are widely utilized as neutron absorbing materials for the storage and transportation of spent nuclear fuel.In order to improve the high-temperature mechanical properties of B_(4)C/Al composites,i...B_(4)C/Al composites are widely utilized as neutron absorbing materials for the storage and transportation of spent nuclear fuel.In order to improve the high-temperature mechanical properties of B_(4)C/Al composites,in-situ nano-Al_(2)O_(3)was introduced utilizing oxide on Al powder surface.In this study,the Al_(2)O_(3)content was adjusted by utilizing spheroid Al powder with varying diameters,thereby investigating the impact of Al_(2)O_(3)content on the tensile properties of(B_(4)C+Al_(2)O_(3))/Al composites.It was found that the pinning effect of Al_(2)O_(3)on the grain boundaries could hinder the recovery of dislocations and lead to dislocation accumulation at high temperature.As the result,with the increase in Al_(2)O_(3)content and the decrease in grain size,the high-temperature strength of the composites increased significantly.The finest Al powder used in this investigation had a diameter of 1.4μm,whereas the resultant composite exhibited a maximum strength of 251 MPa at room temperature and 133 MPa at 350℃,surpassing that of traditional B_(4)C/Al composites.展开更多
基金support of the National Natural Science Foundation of China(Grant Nos.52171056 and 52203385)the Joint Funds of the National Natural Science Foundation of China(Grant Nos.U2341255 and U22A20114)+1 种基金the Young Elite Scientists Sponsorship Program by CAST(Grant No.YESS20220225)the IMR Innovation Fund(Grant No.2021-ZD02).
文摘In dry storage,spent fuel is typically stored in casks constructed from neutron absorbing materials(NAMs).The(B_(4)C+Al_(2)O_(3))/Al composite,which incorporates in-situ amorphous Al_(2)O_(3)(am-Al_(2)O_(3))formed on fine aluminum powder as a reinforcing phase,can serve as an integrated structural and functional NAM for dry storage applications.Welding is crucial in the fabrication of these casks.In this study,friction stir welding was performed on(B_(4)C+Al_(2)O_(3))/Al composite sheets at a welding speed of 50 mm/min and rotation rates ranging from 500 to 1000 r/min.The microstructure of the weld joints was analyzed,and the intrinsic relationship between fracture behavior and microstructure was elucidated.Results showed that defect-free joints were achieved at rotation rates of 500 and 750 r/min,while tunnel defects were observed at 1000 r/min.The ultimate tensile strength of the joint welded at 500 r/min was 205.7 MPa,with a strength efficiency of 82%.Microstructural analysis revealed that the grains within the nugget zones(NZs)coarsened and the Al_(2)O_(3)network was disrupted due to the welding thermo-mechanical effect,resulting in softening within the NZs.Fracture locations for all three joints were consistently observed at the NZ boundary on the advancing side(AS).Finite element simulations confirmed that cracks propagated along the NZ boundary on the AS,where stress concentration occurred during tensile testing.
基金supported by the National Key R&D Program of China(Grant No.2023YFB3710601)the National Natural Science Foundation of China(Grant Nos.52203385 and 52171056)+2 种基金the CNNC Science Fund for Talented Young Scholars,the Institute of Metal Research(IMR)Innovation Fund(Grant No.2021-ZD02)the Natural Science Foundation of Liaoning Province(Grant No.2022-BS-009)Young Elite Scientists Sponsorship Program by CAST(Grant No.YESS20220225).
文摘B_(4)C/Al composites are widely utilized as neutron absorbing materials for the storage and transportation of spent nuclear fuel.In order to improve the high-temperature mechanical properties of B_(4)C/Al composites,in-situ nano-Al_(2)O_(3)was introduced utilizing oxide on Al powder surface.In this study,the Al_(2)O_(3)content was adjusted by utilizing spheroid Al powder with varying diameters,thereby investigating the impact of Al_(2)O_(3)content on the tensile properties of(B_(4)C+Al_(2)O_(3))/Al composites.It was found that the pinning effect of Al_(2)O_(3)on the grain boundaries could hinder the recovery of dislocations and lead to dislocation accumulation at high temperature.As the result,with the increase in Al_(2)O_(3)content and the decrease in grain size,the high-temperature strength of the composites increased significantly.The finest Al powder used in this investigation had a diameter of 1.4μm,whereas the resultant composite exhibited a maximum strength of 251 MPa at room temperature and 133 MPa at 350℃,surpassing that of traditional B_(4)C/Al composites.
