Nanostructured materials with abundant defect sinks show good radiation tolerance due to their efficient absorption of irradiation-induced interstitials and vacancies.However,the poor thermal stability and limited siz...Nanostructured materials with abundant defect sinks show good radiation tolerance due to their efficient absorption of irradiation-induced interstitials and vacancies.However,the poor thermal stability and limited size of such nanomaterials severely limit their practical applications.Herein,we report a novel flexible free-standing network-structured hybrid consisting of amorphous carbon encapsulated nickel nanocrystals anchored on a single-wall carbon nanotube scaffold with excellent radiation tolerance up to 5 dpa at 673 K and exceptional thermal stability up to 1073 K.The nano-scale Ni-SWCNT network with abundant Ni-SWCNT interfaces and grain boundaries provides effective sinks and fast transportation channels for defects,which effectively absorb irradiation-induced defects and improved the irradiation tolerance.Furthermore,the formation of a low-energy Ni-C interface and surface thermal grooves significantly reduces the system free energy and increased thermal stability.The amorphous carbon layer produces an external compressive radial stress that inhibits Ni grain boundaries from migrating,which greatly improves the thermal stability of the hybrid by pinning GBs at grooves between grains and facilitates the annihilation of irradiation-induced defects at the sinks.This work provides a new strategy to improve the thermal stability and radiation tolerance of nano-materials used in an irradiation environment.展开更多
The trade-off between strength and ductility has been an enormous difficulty in the field of materials for an extended time due to their inverse correlation. In this work, friction stir processing(FSP) was for the fir...The trade-off between strength and ductility has been an enormous difficulty in the field of materials for an extended time due to their inverse correlation. In this work, friction stir processing(FSP) was for the first time performed to high-strength and high-melting-point Ni-Co based superalloy(GH4068),and enhanced strength and ductility were achieved in FSP samples. At room temperature, the FSP sample demonstrated significantly higher yield strength and ultimate tensile strength(1290 and 1670 MPa)than that of the base material(BM, 758 and 904 MPa) and advanced wrought GH4068 alloy(982 and 1291 MPa), concurrent with high tensile ductility(~24%). Compared with the BM, 70% higher yield strength of the FSP sample results from the remarkable contribution of grain-boundary and nanotwin strengthening, which has been confirmed by the multimechanistic model studied in this work. More importantly, with increasing temperature, an excellent strength-ductility synergy was obtained at 400 ℃,i.e., the yield strength of the FSP sample was increased by more than 50% compared with the BM(from789 to 1219 MPa);more interestingly, the elongation was also significantly increased from 17.9% in the BM to 28.5% in the FSP sample. Meanwhile, the Portevin-Le Chatelier effect was observed in the engineering stress-strain curve. The occurrence of this effect may be attributed to the interaction between solutes and defects like twins and mobile dislocations. Moreover, the grain refinement mechanism of FSP samples was proved to be discontinuous dynamic recrystallization.展开更多
基金financial support from the Ministry of Science and Technology of China(Nos.2017YFA0700702 and 2017YFA0700705)the National Natural Science Foundation of China(Nos.52073290,51927803,52130209,52188101,12075141,and 11427904)+1 种基金the Science Foundation of Shenyang National Laboratory for Materials Science,Distinguished Young Scholars Foundation of Liaoning Scientific Committee(2023JH6/100500004)Carbon Neutrality Foundation of Shenyang Scientific Committee(21-108-9-01).
文摘Nanostructured materials with abundant defect sinks show good radiation tolerance due to their efficient absorption of irradiation-induced interstitials and vacancies.However,the poor thermal stability and limited size of such nanomaterials severely limit their practical applications.Herein,we report a novel flexible free-standing network-structured hybrid consisting of amorphous carbon encapsulated nickel nanocrystals anchored on a single-wall carbon nanotube scaffold with excellent radiation tolerance up to 5 dpa at 673 K and exceptional thermal stability up to 1073 K.The nano-scale Ni-SWCNT network with abundant Ni-SWCNT interfaces and grain boundaries provides effective sinks and fast transportation channels for defects,which effectively absorb irradiation-induced defects and improved the irradiation tolerance.Furthermore,the formation of a low-energy Ni-C interface and surface thermal grooves significantly reduces the system free energy and increased thermal stability.The amorphous carbon layer produces an external compressive radial stress that inhibits Ni grain boundaries from migrating,which greatly improves the thermal stability of the hybrid by pinning GBs at grooves between grains and facilitates the annihilation of irradiation-induced defects at the sinks.This work provides a new strategy to improve the thermal stability and radiation tolerance of nano-materials used in an irradiation environment.
基金financially supported by the National Key R&D Program of China (Nos.2017YFA0700703 and 2019YFA0705300)the National Natural Science Foundation of China (Grant Nos.11872354 and 11627803)+1 种基金the National Science and Technology Major Project (Grant Nos.J2019-V-0006-0100)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant Nos.XDB22040502)。
文摘The trade-off between strength and ductility has been an enormous difficulty in the field of materials for an extended time due to their inverse correlation. In this work, friction stir processing(FSP) was for the first time performed to high-strength and high-melting-point Ni-Co based superalloy(GH4068),and enhanced strength and ductility were achieved in FSP samples. At room temperature, the FSP sample demonstrated significantly higher yield strength and ultimate tensile strength(1290 and 1670 MPa)than that of the base material(BM, 758 and 904 MPa) and advanced wrought GH4068 alloy(982 and 1291 MPa), concurrent with high tensile ductility(~24%). Compared with the BM, 70% higher yield strength of the FSP sample results from the remarkable contribution of grain-boundary and nanotwin strengthening, which has been confirmed by the multimechanistic model studied in this work. More importantly, with increasing temperature, an excellent strength-ductility synergy was obtained at 400 ℃,i.e., the yield strength of the FSP sample was increased by more than 50% compared with the BM(from789 to 1219 MPa);more interestingly, the elongation was also significantly increased from 17.9% in the BM to 28.5% in the FSP sample. Meanwhile, the Portevin-Le Chatelier effect was observed in the engineering stress-strain curve. The occurrence of this effect may be attributed to the interaction between solutes and defects like twins and mobile dislocations. Moreover, the grain refinement mechanism of FSP samples was proved to be discontinuous dynamic recrystallization.
