High-density stacking faults(SFs)were introduced into a novel Ni-Co-based superalloy through warm rolling at 300-500°C,and the effects of SFs on its tensile properties at intermediate temperatures(650 and 750...High-density stacking faults(SFs)were introduced into a novel Ni-Co-based superalloy through warm rolling at 300-500°C,and the effects of SFs on its tensile properties at intermediate temperatures(650 and 750°C)were investigated.The results indicated that all warm rolled specimens have high-density SFs and Lomer-Cottrell locks compared with the initial specimens.Meanwhile,the simultaneous improvement of intermediate-temperature strength and ductility of alloys can be achieved by high-density SFs.In particular,the specimen rolled at 300°C exhibited a superior combination of high strength(yield and ultimate tensile strengths of(1311±18)and(1462±25)MPa respectively at 650°C,and(1180±17)and(1293±15)MPa respectively at 750°C)and high fracture elongation((26.7±2.5)%at 650°C and(10.7±1.3)%at 750°C).The high strengths and facture elongations of all warm-rolled specimens were primarily attributed to the interaction of pre-existingγ′phases,high-density SFs and Lomer-Cottrell locks with dislocations,as well as to the formation of high-density deformation nano-twins during tensile loading.展开更多
To explain the precipitation mechanism ofχphase in Co-based superalloys,the microstructural evolution of Co−Ti−Mo superalloys subjected to aging was investigated by X-ray diffraction(XRD),scanning electron microscope...To explain the precipitation mechanism ofχphase in Co-based superalloys,the microstructural evolution of Co−Ti−Mo superalloys subjected to aging was investigated by X-ray diffraction(XRD),scanning electron microscope(SEM)and transmission electron microscope(TEM).The results show that the needle-likeχphase is mainly composed ofD0_(19)-Co_(3)(Ti,Mo),which is transformed from L1_(2-γ′)phase,and a specific orientation relationship exists between them.χphase is nucleated through the shearing ofγ′phase due to the influence of stacking fault.The crystal orientation relationship between L1_(2) andD0_(19)can be confirmed as{111}L1_(2)//{0001}_(D0_(19)),and<112>_(L1_(2))//<1100>_(D0_(19)).The growth ofD0_(19-χ)phase depends on the diffusions of Ti and Mo,and consumes a large number of elements.This progress leads to the appearance ofγ′precipitation depletion zone(PDZ)aroundD0_(19-χ)phase.The addition of Ni improves the stability of L1_(2-γ′)phase and the mechanical properties of Co-based superalloys.展开更多
In physics,our expectations for system behavior are often guided by intuitive arithmetic.For systems composed of identical units,we anticipate synergy of the contributions from these units,where 1+1=2.Conversely,for s...In physics,our expectations for system behavior are often guided by intuitive arithmetic.For systems composed of identical units,we anticipate synergy of the contributions from these units,where 1+1=2.Conversely,for systems built from opposing units,we expect cancellation of their contributions,where 1-1=0.This intuitive arithmetic has long underpinned our understanding of physical properties of materials,from electronic transport to optical responses.However,scientific breakthroughs often occur when nature reveals ways to circumvent these seemingly fundamental rules,opening new possibilities that challenge our deepest assumptions about material behavior.展开更多
Implementation of novelγ/γ'Co-based superalloys with higher strength and improved creep durability is a challenging task for researchers.The lack of atomic-level understanding of plastic deformation behavior has...Implementation of novelγ/γ'Co-based superalloys with higher strength and improved creep durability is a challenging task for researchers.The lack of atomic-level understanding of plastic deformation behavior has seriously limited the exploration of the full capacity of Co-based alloys.We put forward a comprehensive study of generalized stacking fault energies by first principles to explore the effect of Ni and Al/W on the plastic deformation mechanism ofγ'precipitates in Co-based superalloys.It is found that alloying Ni and adjusting Al/W obviously change the dislocation glide and twinning nucleation in theγ'precipitates by altering the stable fault energies and the unstable fault energy barriers.Excessive addition of either Ni or W deteriorates the strength even the stability of alloys.The ratio of effective planar fault energy(ΔEp)bridges intrinsic energy barriers and various deformation mechanisms of superalloys at elevated temperatures.Except for alloying effects,the grain orientation also significantly governs the operation of the plastic deformation of superalloys.Our theoretical results agree with the available measurements and well capture the observed phenomena in experiments.展开更多
基金supported by the Program for Hong Liu Excellent Young Scholars by Lanzhou University of Technology in 2023,the National Key Research and Development Program of China(No.2017YFA0700703)the Major Science and Technology Project of Gansu Province,China(Nos.22ZD6GA008,23ZDGC002,23ZDGA010)+1 种基金the Gansu Provincial Key Research and Development Program,China(No.20YF3GA041)the Special Fund of National Key Laboratory of Ni&Co Associated Minerals Resources Development and Comprehensive Utilization by Jinchuan Group Co.,Ltd.,China(No.GZSYS-KY-2022-012).
文摘High-density stacking faults(SFs)were introduced into a novel Ni-Co-based superalloy through warm rolling at 300-500°C,and the effects of SFs on its tensile properties at intermediate temperatures(650 and 750°C)were investigated.The results indicated that all warm rolled specimens have high-density SFs and Lomer-Cottrell locks compared with the initial specimens.Meanwhile,the simultaneous improvement of intermediate-temperature strength and ductility of alloys can be achieved by high-density SFs.In particular,the specimen rolled at 300°C exhibited a superior combination of high strength(yield and ultimate tensile strengths of(1311±18)and(1462±25)MPa respectively at 650°C,and(1180±17)and(1293±15)MPa respectively at 750°C)and high fracture elongation((26.7±2.5)%at 650°C and(10.7±1.3)%at 750°C).The high strengths and facture elongations of all warm-rolled specimens were primarily attributed to the interaction of pre-existingγ′phases,high-density SFs and Lomer-Cottrell locks with dislocations,as well as to the formation of high-density deformation nano-twins during tensile loading.
基金The financial supports from the National Natural Science Foundation of China(Nos.52171107,52201203)the National Natural Science Foundation of China-Joint Fund of Iron and Steel Research(No.U1960204)the“333”Talent Project of Hebei Province,China(No.B20221001)are gratefully acknowledged.
文摘To explain the precipitation mechanism ofχphase in Co-based superalloys,the microstructural evolution of Co−Ti−Mo superalloys subjected to aging was investigated by X-ray diffraction(XRD),scanning electron microscope(SEM)and transmission electron microscope(TEM).The results show that the needle-likeχphase is mainly composed ofD0_(19)-Co_(3)(Ti,Mo),which is transformed from L1_(2-γ′)phase,and a specific orientation relationship exists between them.χphase is nucleated through the shearing ofγ′phase due to the influence of stacking fault.The crystal orientation relationship between L1_(2) andD0_(19)can be confirmed as{111}L1_(2)//{0001}_(D0_(19)),and<112>_(L1_(2))//<1100>_(D0_(19)).The growth ofD0_(19-χ)phase depends on the diffusions of Ti and Mo,and consumes a large number of elements.This progress leads to the appearance ofγ′precipitation depletion zone(PDZ)aroundD0_(19-χ)phase.The addition of Ni improves the stability of L1_(2-γ′)phase and the mechanical properties of Co-based superalloys.
基金supported by the National Natural Science Foundation of China (Grant No.12374109)the National Key Research and Development Program of China (Grant No.2023YFA1406600)。
文摘In physics,our expectations for system behavior are often guided by intuitive arithmetic.For systems composed of identical units,we anticipate synergy of the contributions from these units,where 1+1=2.Conversely,for systems built from opposing units,we expect cancellation of their contributions,where 1-1=0.This intuitive arithmetic has long underpinned our understanding of physical properties of materials,from electronic transport to optical responses.However,scientific breakthroughs often occur when nature reveals ways to circumvent these seemingly fundamental rules,opening new possibilities that challenge our deepest assumptions about material behavior.
基金financially supported by the National Natural Science Foundation of China(No.51601161)the Youth Innovation Fund Project of Xiamen(No.3502Z20206057)the Natural Science Foundation of Fujian Province of China(No.2020J01051)。
文摘Implementation of novelγ/γ'Co-based superalloys with higher strength and improved creep durability is a challenging task for researchers.The lack of atomic-level understanding of plastic deformation behavior has seriously limited the exploration of the full capacity of Co-based alloys.We put forward a comprehensive study of generalized stacking fault energies by first principles to explore the effect of Ni and Al/W on the plastic deformation mechanism ofγ'precipitates in Co-based superalloys.It is found that alloying Ni and adjusting Al/W obviously change the dislocation glide and twinning nucleation in theγ'precipitates by altering the stable fault energies and the unstable fault energy barriers.Excessive addition of either Ni or W deteriorates the strength even the stability of alloys.The ratio of effective planar fault energy(ΔEp)bridges intrinsic energy barriers and various deformation mechanisms of superalloys at elevated temperatures.Except for alloying effects,the grain orientation also significantly governs the operation of the plastic deformation of superalloys.Our theoretical results agree with the available measurements and well capture the observed phenomena in experiments.
