Bulk metallic glass (BMG) composites with the austenite B2 phase as reinforcement macroscopically showed strain hardening behavior due to the plasticity induced by martensitic transformation during deformation. Relati...Bulk metallic glass (BMG) composites with the austenite B2 phase as reinforcement macroscopically showed strain hardening behavior due to the plasticity induced by martensitic transformation during deformation. Relationship between characteristics of the B2-CuZr reinforcing phase and uniaxial compressive properties of CuZr-based BMG composites was studied. Mechanical properties of these BMG composites were found to depend on not only the reinforced phases but also the amorphous matrix,and the yield and fracture strength can be roughly estimated by the rule of mixture principle. Distribution of the reinforced B2-CuZr phase has an important impact on the compressive plasticity even for the composites with a similar volume fraction of the crystalline phase.展开更多
In this manuscript, the FeCrCoNi high entropy alloy strengthened by nano-Y203 particles was synthesized via mechanical alloying and spark plasma sintering. Effects of Y203 additions on the microstructure and mechanica...In this manuscript, the FeCrCoNi high entropy alloy strengthened by nano-Y203 particles was synthesized via mechanical alloying and spark plasma sintering. Effects of Y203 additions on the microstructure and mechanical properties were investigated. The oxide-dispersion-strengthened （ODS） high-entropy alloy bearing 5wt% Y203 was found to have a finer grain with respect to the single-phase face-centered cubic （FCC） alloy without oxides. Consequently, the yield strength increased from 654 to 1754 MPa, and the fracture strength reached up to 2325 MPa while the plasticity decreased appreciably for the ODS high-entropy alloy. The synergic effects of grain size hardening and particle strengthening on mechanical properties of the ODS HEA were discussed. This finding indicates that the addition of nano-scaled oxides is an effective and feasible approach to designing HEAs with superior mechanical properties.展开更多
The effects of Sn and Ga additions on the glass forming ability （GFA） of （A186LasNi9）100_xSnx（x=0, 0.2, 0.3, 0.5, 0.7, 1 and 2 at.%） and （Al86LasNi9）100_xGax（x=0, 0.2, 0.5, 1 and 1.5 at.%） alloys were system...The effects of Sn and Ga additions on the glass forming ability （GFA） of （A186LasNi9）100_xSnx（x=0, 0.2, 0.3, 0.5, 0.7, 1 and 2 at.%） and （Al86LasNi9）100_xGax（x=0, 0.2, 0.5, 1 and 1.5 at.%） alloys were systematically investigated. Unlike common microal- loying methods, both Sn and Ga have a positive heat of mixing with the main component of A1. Our analysis confirmed that proper Sn addition can suppress the strong formation of a-A1 and enhance the GFA due to the positive heat of mixing between Sn and AI and the large difference in their atomic sizes. While the addition of Ga to the base alloy acted as the nucleation cites for ct-Al and accelerated precipitation of the ct-A1 phase, thus deteriorating the GFA.展开更多
Lead-bismuth eutectics (LBE) have considerable potential as a candidate material for accelerator-driven sub-critical systems(ADS).However,LBE corrosion and irradiation damage are two urgent challenges remaining to be ...Lead-bismuth eutectics (LBE) have considerable potential as a candidate material for accelerator-driven sub-critical systems(ADS).However,LBE corrosion and irradiation damage are two urgent challenges remaining to be solved for impellers of primary pumps.In this study,we have explored the possibility of using Fe-based amorphous coatings to overcome LBE corrosion and concurrently to sustain irradiation damage.Specifically,the Fe_(54)Cr_(18)Mo_(2)Zr_(8)B_(18)amorphous coating was prepared by high-velocity oxygen-fuel (HVOF) spraying on 316L steel and exposed to saturated oxygen static LBE for 500 h at 400℃.The coating with high thermal stability (T_(g)=615℃ and T_(x)=660℃) effectively prevented the substrate steel from being corroded by LBE owing to its unique long-range disordered atomic packing.The coating also exhibited strong irradiation resistance when being subjected to 45 dpa (displacement per atom) Au ion irradiation at room temperature,with no sign of crystallization even at the maximum implantation depth of 300 nm.Consequently,the hardness of the coatings before and after irradiation increased slightly.The current findings shed new insights into understanding corrosion mechanism and irradiation behavior of amorphous solids in LBE and expand the application range of amorphous materials.展开更多
In this work,we develop a new many-body potential for alpha-hafnium(α-Hf)based on the second moment approximation of tight-binding(TB-SMA)theory by introducing an additional Heaviside step function into the potential...In this work,we develop a new many-body potential for alpha-hafnium(α-Hf)based on the second moment approximation of tight-binding(TB-SMA)theory by introducing an additional Heaviside step function into the potential model and a new analytical scheme of density function.All the parameters of the new potential have been systematically evaluated by fitting to ground-state properties including cohesive energy,lattice constants,elastic constants,vacancy formation energy,structure stability and equation of state.By using the present model,the melting point,melt heat,thermal expansion coefficient,point defects,and low-index surface energies ofα-Hf were calculated through molecular dynamics simulations.Comparing with experiment observations from others,it is shown that these properties can be reproduced reasonably by the present model,some results being more consistent to the experimental data than those by previous suggested models.This indicates that this work is sutiable in TB-SMA potential for hexagonal close packed metals.展开更多
Generally, two approaches were employed to develop stronger materials： one is to increase dislocations densi- ties or/and impede their motions, such as solid solution strengthening, grain refinement strengthening and...Generally, two approaches were employed to develop stronger materials： one is to increase dislocations densi- ties or/and impede their motions, such as solid solution strengthening, grain refinement strengthening and precipitate strengthening; the other is amorphization which completely eliminates dislocations, and the deformation mechanism also changes from a dislocation-activated mode to the activation of shear bands. However, too much defects can cause a defect-softening behavior. For example,展开更多
基金supported in part by the National Natural Science Foundation of China (50725104, 51010001 and 51001009)China Postdoctoral Science Foundation (20100470208) the Fundamental Research Funds for the Central Universities (FRF-BR-10-036B)
文摘Bulk metallic glass (BMG) composites with the austenite B2 phase as reinforcement macroscopically showed strain hardening behavior due to the plasticity induced by martensitic transformation during deformation. Relationship between characteristics of the B2-CuZr reinforcing phase and uniaxial compressive properties of CuZr-based BMG composites was studied. Mechanical properties of these BMG composites were found to depend on not only the reinforced phases but also the amorphous matrix,and the yield and fracture strength can be roughly estimated by the rule of mixture principle. Distribution of the reinforced B2-CuZr phase has an important impact on the compressive plasticity even for the composites with a similar volume fraction of the crystalline phase.
基金supported by the National Natural Science Foundation of China(Grant Nos.51671018,51671021&51531001)Higher Education Discipline Innovation Project(Grant No.B07003)+2 种基金International S&T Cooperation Program of China(Grant No.2015DFG52600)the Program for Changjiang Scholars and Innovative Research Team in University of China(Grant No.IRT_14R05)the Projects of SKL-AMM-USTB(Grant Nos.2016Z-04,2016-09&2016Z-16)
文摘In this manuscript, the FeCrCoNi high entropy alloy strengthened by nano-Y203 particles was synthesized via mechanical alloying and spark plasma sintering. Effects of Y203 additions on the microstructure and mechanical properties were investigated. The oxide-dispersion-strengthened （ODS） high-entropy alloy bearing 5wt% Y203 was found to have a finer grain with respect to the single-phase face-centered cubic （FCC） alloy without oxides. Consequently, the yield strength increased from 654 to 1754 MPa, and the fracture strength reached up to 2325 MPa while the plasticity decreased appreciably for the ODS high-entropy alloy. The synergic effects of grain size hardening and particle strengthening on mechanical properties of the ODS HEA were discussed. This finding indicates that the addition of nano-scaled oxides is an effective and feasible approach to designing HEAs with superior mechanical properties.
基金supported by the National Natural Science Foundation of China(Grant Nos.51010001 and 51001009)the 111 Project(Grant No.B07003)the Program for Changjiang Scholars and Innovative Research Team in University
文摘The effects of Sn and Ga additions on the glass forming ability （GFA） of （A186LasNi9）100_xSnx（x=0, 0.2, 0.3, 0.5, 0.7, 1 and 2 at.%） and （Al86LasNi9）100_xGax（x=0, 0.2, 0.5, 1 and 1.5 at.%） alloys were systematically investigated. Unlike common microal- loying methods, both Sn and Ga have a positive heat of mixing with the main component of A1. Our analysis confirmed that proper Sn addition can suppress the strong formation of a-A1 and enhance the GFA due to the positive heat of mixing between Sn and AI and the large difference in their atomic sizes. While the addition of Ga to the base alloy acted as the nucleation cites for ct-Al and accelerated precipitation of the ct-A1 phase, thus deteriorating the GFA.
基金supported by the National Natural Science Foundation of China(Grant Nos.51871016,51671018,11790293,51921001,51671018)111 Project(Grant No.BP0719004)+3 种基金the Program for Changjiang Scholars and Innovative Research Team in University of China(Grant No.IRT_14R05)the Projects of SKLAMM-USTB(Grant Nos.2018Z-01,2018Z-19)the financial support from the Top-Notch Young Talents Programthe financial support from the Fundamental Research Funds for the Central Universities(Grant No.FRF-TP-18-004C1)。
文摘Lead-bismuth eutectics (LBE) have considerable potential as a candidate material for accelerator-driven sub-critical systems(ADS).However,LBE corrosion and irradiation damage are two urgent challenges remaining to be solved for impellers of primary pumps.In this study,we have explored the possibility of using Fe-based amorphous coatings to overcome LBE corrosion and concurrently to sustain irradiation damage.Specifically,the Fe_(54)Cr_(18)Mo_(2)Zr_(8)B_(18)amorphous coating was prepared by high-velocity oxygen-fuel (HVOF) spraying on 316L steel and exposed to saturated oxygen static LBE for 500 h at 400℃.The coating with high thermal stability (T_(g)=615℃ and T_(x)=660℃) effectively prevented the substrate steel from being corroded by LBE owing to its unique long-range disordered atomic packing.The coating also exhibited strong irradiation resistance when being subjected to 45 dpa (displacement per atom) Au ion irradiation at room temperature,with no sign of crystallization even at the maximum implantation depth of 300 nm.Consequently,the hardness of the coatings before and after irradiation increased slightly.The current findings shed new insights into understanding corrosion mechanism and irradiation behavior of amorphous solids in LBE and expand the application range of amorphous materials.
基金supported by the National Natural Science Foundation of China(Grant Nos.51071018 and 51271018)
文摘In this work,we develop a new many-body potential for alpha-hafnium(α-Hf)based on the second moment approximation of tight-binding(TB-SMA)theory by introducing an additional Heaviside step function into the potential model and a new analytical scheme of density function.All the parameters of the new potential have been systematically evaluated by fitting to ground-state properties including cohesive energy,lattice constants,elastic constants,vacancy formation energy,structure stability and equation of state.By using the present model,the melting point,melt heat,thermal expansion coefficient,point defects,and low-index surface energies ofα-Hf were calculated through molecular dynamics simulations.Comparing with experiment observations from others,it is shown that these properties can be reproduced reasonably by the present model,some results being more consistent to the experimental data than those by previous suggested models.This indicates that this work is sutiable in TB-SMA potential for hexagonal close packed metals.
文摘Generally, two approaches were employed to develop stronger materials： one is to increase dislocations densi- ties or/and impede their motions, such as solid solution strengthening, grain refinement strengthening and precipitate strengthening; the other is amorphization which completely eliminates dislocations, and the deformation mechanism also changes from a dislocation-activated mode to the activation of shear bands. However, too much defects can cause a defect-softening behavior. For example,
