Ti-Zr-Nb refractory multi-principal element alloys(RMPEAs)have attracted increased attention due to their excellent mechanical properties.In this study,(TiZr)_(80-x)Nb_(20)Mo_(x)(x=0,5 and 10)alloys were designed,and ...Ti-Zr-Nb refractory multi-principal element alloys(RMPEAs)have attracted increased attention due to their excellent mechanical properties.In this study,(TiZr)_(80-x)Nb_(20)Mo_(x)(x=0,5 and 10)alloys were designed,and the intrinsic conflicts between strength and ductility were overcome via composition optimization and recrystallization.The causes of the superior strength-ductility synergy were investigated in terms of their deformation mechanism and dislocation behavior.The results show that the strength improvement can be attributed to the deformation mechanism transition caused by local chemical fluctuations and lattice distortion.Specifically,the slip band widths decrease after Mo addition,and the measured slip traces in the fracture samples are associated with high-order{112}and{123}slip planes.Furthermore,the grain refinement achieved via recrystallization promotes multi-slip system activation and shortens the slip-band spacing,which reduces the stress concentration and inhibits crack source formation,thereby allowing the alloy to ensure sufficient ductility.Consequently,the Ti_(35)Zr_(35)Nb_(20)Mo_(10)alloy annealed at 900℃ exhibits high yield strength and elongation.These findings provide a new strategy for designing high-strength RMPEAs and addressing room-temperature brittleness.展开更多
This research presents a thorough assessment of the cyclic oxidation characteristics of Y-and Hf-doped NiCoCrAlTaRe superalloy bond coatings in a pure steam atmosphere,emphasizing the distinct influences of reactive e...This research presents a thorough assessment of the cyclic oxidation characteristics of Y-and Hf-doped NiCoCrAlTaRe superalloy bond coatings in a pure steam atmosphere,emphasizing the distinct influences of reactive elements (Y and Hf) and refractory elements (Ta and Re)on the growth mechanisms of thermally grown oxide(TGO).The findings indicate that,in contrast to air conditions,elevated levels of water vapor significantly diminish the oxidation resistance of the bond coatings,leading to considerable porosity defects in both the central and lower regions of the TGO.Furthermore,this environment hinders the development of the"peg"structure at the TGO/metal interface,thereby accelerating the premature delamination of the coating.Additionally,the presence of doped elements such as Hf,Ta,and Y leads to their segregation at the Al_(2)O_(3)grain boundaries within the TGO,creating grain boundary structures characterized by a high density of defects.This defective architecture promotes the inward diffusion of water molecules at elevatedtemperatures,causing hydrogen atoms generated from oxidation and reduction reactions at the TGO/metal interface to become entrapped within the Al_(2)O_(3)lattice at the base of the TGO,rather than escaping efficiently.Ultimately,this phenomenon contributes to the formation of internal porosity defects during the oxidation of TGO in a steam environment.展开更多
Due to the outstanding creep performance, nickel-based single crystal superalloys(Ni-SXs) are extensively applied in modern aero-engine and industrial gas turbine. Apart from the special single crystal structure which...Due to the outstanding creep performance, nickel-based single crystal superalloys(Ni-SXs) are extensively applied in modern aero-engine and industrial gas turbine. Apart from the special single crystal structure which is disadvantageous to extension of creep cracks, Ni-SXs derive the creep strength from intrinsic two-phase microstructure(γ phase and γ’ phase). Main microstructural parameters including volume fraction of γ’ phase and the lattice misfit, and the formation and distribution of precipitated phase are determined by the compositions of alloys. Besides, the creep properties are greatly influenced by these microstructural parameters and precipitated phase. This review has summarized the relationships between different alloying elements and microstructures and indicated their influence on creep properties of Ni-SXs. In addition, with the improvements of experimental methods and characterization technique, some recent discoveries have provided additional evidence to support or challenge the pervious creep theories of superalloys. In view of these new discoveries, this review has provided some perspectives which can be referenced in future compositional design of Ni-SXs.展开更多
Advanced structural materials with superb mechanical properties at ultrahigh temperatures are essential for aerospace and power-generation sectors.Refractory multi-principal element alloys(RMPEAs)are promising candida...Advanced structural materials with superb mechanical properties at ultrahigh temperatures are essential for aerospace and power-generation sectors.Refractory multi-principal element alloys(RMPEAs)are promising candidates,but they face challenges such as limited plasticity at room temperatures and insufficient strength at ultrahigh temperatures.In this work,we investigated the mechanical properties and microstructures of RMPEA reinforced with compositional complex carbides and demonstrated that tailoring the carbon content can significantly alter their microstructures and enhance mechanical properties.Specifically,the W_(30)Ta_(30)Mo_(15)Nb_(15)C_(10)alloy achieved an ultrahigh strength of 896 MPa at 1600℃ and a plasticity of∼8%at room temperatures.The strengthening effect arises from multi-principal element mixing and robust dislocation hindering at the phase interfaces between the carbides and the matrix,while the room temperature plasticity is attributed to crack buffering facilitated by the highly saturated solid solution matrix.Our study highlights the potential of compositional complex carbide to enhance the mechanical properties of RMPEAs,offering a promising approach for the development of advanced structural materials for ultrahigh temperature applications.展开更多
To improve strength and ductility of Ti-Zr-Nb lightweight refractory multi-principal element alloys(LRMPEAs)simultaneously,which is difficult for traditional solution strengthening and second-phase/precipitate strengt...To improve strength and ductility of Ti-Zr-Nb lightweight refractory multi-principal element alloys(LRMPEAs)simultaneously,which is difficult for traditional solution strengthening and second-phase/precipitate strengthening,the compositional inhomogeneity in TiZrNb ternary equimolar LRMPEAs with a single-phased body-centered cubic structure is stimulated and tailored by doping V element.When V is introduced,compositional inhomogeneity shows as the segregation of V and Zr elements form.As the value of x for TiZrNbV_(x)LRMPEAs increases from 0.3 to 0.6,the mild compositional fluctuation develops to the spinodal decomposition structured three-dimensional framework with a periodicity of~5 nm.Then the dislocations in TiZrNbV_(0.6)LRMPEA are compactly pinned,a remarkable strengthening effect(~120 MPa)while the Frank-Read sources for dislocation multiplication and cross-slip are stimulated.Thus,an optimal combination of strength and ductility including the yield strength of 883 MPa and the fracture elongation of 26.6%is achieved in TiZrNbV0.6 LRMPEA.This work provides a useful method to enhance the strength of Ti-Zr-Nb LRMPEAs without sacrificing the ductility.This way is expected to be effective for other multi-principal element alloys,including high-entropy alloys and medium-entropy alloys.展开更多
Oxygen-induced microstructural evolution critically governs the long-term reliability of refractory multi-principal element alloys(RMPEAs)in extreme environments,where oxygen ingress during prolonged high-temperature ...Oxygen-induced microstructural evolution critically governs the long-term reliability of refractory multi-principal element alloys(RMPEAs)in extreme environments,where oxygen ingress during prolonged high-temperature service can drastically alter micro structural stability and mechanical performance,yet its atomic-scale mechanisms remain poorly understood.Here,oxygen's dual role in NbZrTi-based RMPEAs is systematically revealed through aging experiments at 650℃for 48and 168 h,combined with multiscale characterization.High-oxygen alloys(3 at.%O)exhibited multi-phase precipitation,including Zr-O-enriched hexagonal close-packed and dual body-centered cubic phases(Zr+Ti-O-rich and Nb+Ti-rich),governed by oxygen redistribution and thermodynamic stabilization.Contrary to conventional precipitation hardening,oxygen segregation gradients at the grain boundaries induced lattice distortion mitigation in the matrix,leading to a twostage age-softening behavior:rapid initial hardness reduction(20%within 48 h)followed by a plateau regime.The interplay between oxygen-mediated phase separation and concentration-dependent solute partitioning highlights the delicate balance required to optimize RMPEAs for high-temperature applications.These findings establish oxygen concentration thresholds and grain boundary engineering as critical design parameters for RMPEAs,enabling simultaneous optimization of radiation resistance and century-scale stability in next-generation nuclear reactor structure materials.展开更多
The traditional trial-and-error method for designing refractory multi-principal element alloys(RMPEAs)is inefficient due to a vast compositional design space and high experimental costs.To surmount this challenge,the ...The traditional trial-and-error method for designing refractory multi-principal element alloys(RMPEAs)is inefficient due to a vast compositional design space and high experimental costs.To surmount this challenge,the data-driven material design based on machine learning(ML)has emerged as a critical tool for accelerating materials design.However,the absence of robust datasets impedes the exploitation of machine learning in designing novel RMPEAs.High-throughput(HTP)calculations have enabled the creation of such datasets.This study addresses these challenges by developing a data-driven framework for predicting the elastic properties of RMPEAs,integrating HTP calculations with ML.A big dataset of RMPEAs including 4536 compositions was constructed using the new proposed HTP method.A novel stacking ensemble regression algorithm combining multilayer perceptron(MLP)and gradient boosting decision tree(GBDT)was developed,which achieved 92.9%accuracy in predicting the elastic properties of Ti-V-Nb-Ta alloys.Verification experiments confirmed the ML model's accuracy and robustness.This integration of HTP calculations and ML provides a costeffective,efficient,and precise alloy design strategy,advancing RMPEAs development.展开更多
To meet the increasing demand for continuously enhancing engineering performance and energy efficiency in a variety of aerospace and energy applications,structural materials with high strength at ultra-high temperatur...To meet the increasing demand for continuously enhancing engineering performance and energy efficiency in a variety of aerospace and energy applications,structural materials with high strength at ultra-high temperatures are urgently required.In the past decade,refractory multi-principal element alloys(RMPEAs),particularly those containing elements with high melting temperatures(T_(m))such as W and Ta(hereafter denoted as WTa-RMPEAs),have garnered extensive interest due to their exceptional strengths and thermally stability at high temperatures.Characterized by high T_(m),sluggish diffusion,and severe lattice distortion,WTa-RMPEAs exhibit chemical composition fluctuations at different scales,leading to unique mechanical properties and deformation behavior.In this paper,an initial summary is provided of the mechanical properties of typical WTa-RMPEAs at room and high temperatures and the differences in deformation behavior and underlying mechanisms between RMPEAs and conventional alloys are discussed.Additionally,strengthening and toughening strategies and the suggested deformation mechanisms were reviewed.Finally,the challenges in revealing the actual deformation mechanism of WTa-RMPEAs were described,and a brief perspective on the future research of the mechanical behavior of WTa-RMPEAs was proposed.展开更多
基金supported by the National Key Research and Development Program of China(No.2022YFF0609000)the National Natural Science Foundation of China(Nos.52171034 and 52101037)the Postdoctoral Fellowship Program of CPSF(No.GZB20230944).
文摘Ti-Zr-Nb refractory multi-principal element alloys(RMPEAs)have attracted increased attention due to their excellent mechanical properties.In this study,(TiZr)_(80-x)Nb_(20)Mo_(x)(x=0,5 and 10)alloys were designed,and the intrinsic conflicts between strength and ductility were overcome via composition optimization and recrystallization.The causes of the superior strength-ductility synergy were investigated in terms of their deformation mechanism and dislocation behavior.The results show that the strength improvement can be attributed to the deformation mechanism transition caused by local chemical fluctuations and lattice distortion.Specifically,the slip band widths decrease after Mo addition,and the measured slip traces in the fracture samples are associated with high-order{112}and{123}slip planes.Furthermore,the grain refinement achieved via recrystallization promotes multi-slip system activation and shortens the slip-band spacing,which reduces the stress concentration and inhibits crack source formation,thereby allowing the alloy to ensure sufficient ductility.Consequently,the Ti_(35)Zr_(35)Nb_(20)Mo_(10)alloy annealed at 900℃ exhibits high yield strength and elongation.These findings provide a new strategy for designing high-strength RMPEAs and addressing room-temperature brittleness.
基金financially supported by the National Key R&D Program of China(No.2023YFB3711200)the National Natural Science Foundation of China(No.U21A2044)the Science Center for Gas Turbine Project(No.P2022-B-IV-008-001)
文摘This research presents a thorough assessment of the cyclic oxidation characteristics of Y-and Hf-doped NiCoCrAlTaRe superalloy bond coatings in a pure steam atmosphere,emphasizing the distinct influences of reactive elements (Y and Hf) and refractory elements (Ta and Re)on the growth mechanisms of thermally grown oxide(TGO).The findings indicate that,in contrast to air conditions,elevated levels of water vapor significantly diminish the oxidation resistance of the bond coatings,leading to considerable porosity defects in both the central and lower regions of the TGO.Furthermore,this environment hinders the development of the"peg"structure at the TGO/metal interface,thereby accelerating the premature delamination of the coating.Additionally,the presence of doped elements such as Hf,Ta,and Y leads to their segregation at the Al_(2)O_(3)grain boundaries within the TGO,creating grain boundary structures characterized by a high density of defects.This defective architecture promotes the inward diffusion of water molecules at elevatedtemperatures,causing hydrogen atoms generated from oxidation and reduction reactions at the TGO/metal interface to become entrapped within the Al_(2)O_(3)lattice at the base of the TGO,rather than escaping efficiently.Ultimately,this phenomenon contributes to the formation of internal porosity defects during the oxidation of TGO in a steam environment.
基金This work was jointly supported by the Fundamental Research Funds for the Central Universities(No.2019QNA4012)the Innovation Fund of the Zhejiang Kechuang New Materials Research Institute(No.ZKN-18-Z01).
文摘Due to the outstanding creep performance, nickel-based single crystal superalloys(Ni-SXs) are extensively applied in modern aero-engine and industrial gas turbine. Apart from the special single crystal structure which is disadvantageous to extension of creep cracks, Ni-SXs derive the creep strength from intrinsic two-phase microstructure(γ phase and γ’ phase). Main microstructural parameters including volume fraction of γ’ phase and the lattice misfit, and the formation and distribution of precipitated phase are determined by the compositions of alloys. Besides, the creep properties are greatly influenced by these microstructural parameters and precipitated phase. This review has summarized the relationships between different alloying elements and microstructures and indicated their influence on creep properties of Ni-SXs. In addition, with the improvements of experimental methods and characterization technique, some recent discoveries have provided additional evidence to support or challenge the pervious creep theories of superalloys. In view of these new discoveries, this review has provided some perspectives which can be referenced in future compositional design of Ni-SXs.
基金financially supported by the National Natural Science Foundation of China(Nos.52201171,52225103,U2441262,51921001,and 12335017)the Fundamental Research Funds for the Central Universities,China(No.FRF-IDRY-23-001)+1 种基金National Key Re-search and Development Program of China(No.2022YFB4602101)the China heavy-duty gas turbine technology Co.Ltd under the project of J721.
文摘Advanced structural materials with superb mechanical properties at ultrahigh temperatures are essential for aerospace and power-generation sectors.Refractory multi-principal element alloys(RMPEAs)are promising candidates,but they face challenges such as limited plasticity at room temperatures and insufficient strength at ultrahigh temperatures.In this work,we investigated the mechanical properties and microstructures of RMPEA reinforced with compositional complex carbides and demonstrated that tailoring the carbon content can significantly alter their microstructures and enhance mechanical properties.Specifically,the W_(30)Ta_(30)Mo_(15)Nb_(15)C_(10)alloy achieved an ultrahigh strength of 896 MPa at 1600℃ and a plasticity of∼8%at room temperatures.The strengthening effect arises from multi-principal element mixing and robust dislocation hindering at the phase interfaces between the carbides and the matrix,while the room temperature plasticity is attributed to crack buffering facilitated by the highly saturated solid solution matrix.Our study highlights the potential of compositional complex carbide to enhance the mechanical properties of RMPEAs,offering a promising approach for the development of advanced structural materials for ultrahigh temperature applications.
基金supported by the National Natural Science Foundation of China(Nos.52171166,52471190,and U20A20231)the Natural Science Foundation of Hunan Province,China(Nos.2024JJ2060 and 2024JJ5406)+1 种基金Key Laboratory of Materials in Dynamic Extremes of Sichuan Province(No.2023SCKT1102)supported by Sinoma Institute of Materials Research(Guang Zhou)Co.,Ltd。
文摘To improve strength and ductility of Ti-Zr-Nb lightweight refractory multi-principal element alloys(LRMPEAs)simultaneously,which is difficult for traditional solution strengthening and second-phase/precipitate strengthening,the compositional inhomogeneity in TiZrNb ternary equimolar LRMPEAs with a single-phased body-centered cubic structure is stimulated and tailored by doping V element.When V is introduced,compositional inhomogeneity shows as the segregation of V and Zr elements form.As the value of x for TiZrNbV_(x)LRMPEAs increases from 0.3 to 0.6,the mild compositional fluctuation develops to the spinodal decomposition structured three-dimensional framework with a periodicity of~5 nm.Then the dislocations in TiZrNbV_(0.6)LRMPEA are compactly pinned,a remarkable strengthening effect(~120 MPa)while the Frank-Read sources for dislocation multiplication and cross-slip are stimulated.Thus,an optimal combination of strength and ductility including the yield strength of 883 MPa and the fracture elongation of 26.6%is achieved in TiZrNbV0.6 LRMPEA.This work provides a useful method to enhance the strength of Ti-Zr-Nb LRMPEAs without sacrificing the ductility.This way is expected to be effective for other multi-principal element alloys,including high-entropy alloys and medium-entropy alloys.
基金supported by the National Natural Science Foundation of China(Nos.12305290,U2441258,52231001)the Postdoctoral Fellowship Program of CPSF(No.GZC20232089)+1 种基金the Innovative Scientific Program of China National Nuclear Corporationthe Fundamental Research Funds for the Central Universities。
文摘Oxygen-induced microstructural evolution critically governs the long-term reliability of refractory multi-principal element alloys(RMPEAs)in extreme environments,where oxygen ingress during prolonged high-temperature service can drastically alter micro structural stability and mechanical performance,yet its atomic-scale mechanisms remain poorly understood.Here,oxygen's dual role in NbZrTi-based RMPEAs is systematically revealed through aging experiments at 650℃for 48and 168 h,combined with multiscale characterization.High-oxygen alloys(3 at.%O)exhibited multi-phase precipitation,including Zr-O-enriched hexagonal close-packed and dual body-centered cubic phases(Zr+Ti-O-rich and Nb+Ti-rich),governed by oxygen redistribution and thermodynamic stabilization.Contrary to conventional precipitation hardening,oxygen segregation gradients at the grain boundaries induced lattice distortion mitigation in the matrix,leading to a twostage age-softening behavior:rapid initial hardness reduction(20%within 48 h)followed by a plateau regime.The interplay between oxygen-mediated phase separation and concentration-dependent solute partitioning highlights the delicate balance required to optimize RMPEAs for high-temperature applications.These findings establish oxygen concentration thresholds and grain boundary engineering as critical design parameters for RMPEAs,enabling simultaneous optimization of radiation resistance and century-scale stability in next-generation nuclear reactor structure materials.
基金Funding for this research was provided by the Yunnan Provincial Science and Technology Department(Grant Nos.202302AB080023,202402AC080002,202303AA080015,202301BC070001-001)the Open Projects of Yunnan Precious Metals Laboratory Co.,Ltd(Grant Nos.YPML-20240502046,YPML-2023050205,YPML-2023050254)+1 种基金Yunnan Fundamental Research Projects(Grant No.202201AT070161)Revitalizing Yunnan Talents Support Plan and Yunnan Province High-level Talent Introduction Program(C619300A023,K264204240011).C.Jin received partial support from the HZWTECH-PROP projects.
文摘The traditional trial-and-error method for designing refractory multi-principal element alloys(RMPEAs)is inefficient due to a vast compositional design space and high experimental costs.To surmount this challenge,the data-driven material design based on machine learning(ML)has emerged as a critical tool for accelerating materials design.However,the absence of robust datasets impedes the exploitation of machine learning in designing novel RMPEAs.High-throughput(HTP)calculations have enabled the creation of such datasets.This study addresses these challenges by developing a data-driven framework for predicting the elastic properties of RMPEAs,integrating HTP calculations with ML.A big dataset of RMPEAs including 4536 compositions was constructed using the new proposed HTP method.A novel stacking ensemble regression algorithm combining multilayer perceptron(MLP)and gradient boosting decision tree(GBDT)was developed,which achieved 92.9%accuracy in predicting the elastic properties of Ti-V-Nb-Ta alloys.Verification experiments confirmed the ML model's accuracy and robustness.This integration of HTP calculations and ML provides a costeffective,efficient,and precise alloy design strategy,advancing RMPEAs development.
基金supported by the National Natural Science Foundation of China(Nos.52201171,52225103,12335017)the Fundamental Research Funds for the Central Universities,China(No.FRF-IDRY-23-001)+1 种基金the Funds for Creative Research Groups of China(No.51921001)China United Gas Turbin Technology Co.,Ltd.under the project of J721.
文摘To meet the increasing demand for continuously enhancing engineering performance and energy efficiency in a variety of aerospace and energy applications,structural materials with high strength at ultra-high temperatures are urgently required.In the past decade,refractory multi-principal element alloys(RMPEAs),particularly those containing elements with high melting temperatures(T_(m))such as W and Ta(hereafter denoted as WTa-RMPEAs),have garnered extensive interest due to their exceptional strengths and thermally stability at high temperatures.Characterized by high T_(m),sluggish diffusion,and severe lattice distortion,WTa-RMPEAs exhibit chemical composition fluctuations at different scales,leading to unique mechanical properties and deformation behavior.In this paper,an initial summary is provided of the mechanical properties of typical WTa-RMPEAs at room and high temperatures and the differences in deformation behavior and underlying mechanisms between RMPEAs and conventional alloys are discussed.Additionally,strengthening and toughening strategies and the suggested deformation mechanisms were reviewed.Finally,the challenges in revealing the actual deformation mechanism of WTa-RMPEAs were described,and a brief perspective on the future research of the mechanical behavior of WTa-RMPEAs was proposed.
