THE mechanical response and deformation mechanisms of pure nickel under nanoindentation were systematically investigated using molecular dynamics(MD)simulations,with a particular focus on the novel interplay between c...THE mechanical response and deformation mechanisms of pure nickel under nanoindentation were systematically investigated using molecular dynamics(MD)simulations,with a particular focus on the novel interplay between crystallographic orientation,grain boundary(GB)proximity,and pore characteristics(size/location).This study compares single-crystal nickel models along[100],[110],and[111]orientations with equiaxed polycrystalline models containing 0,1,and 2.5 nm pores in surface and subsurface configurations.Our results reveal that crystallographic anisotropy manifests as a 24.4%higher elastic modulus and 22.2%greater hardness in[111]-oriented single crystals compared to[100].Pore-GB synergistic effects are found to dominate the deformation behavior:2.5 nm subsurface pores reduce hardness by 25.2%through stress concentration and dislocation annihilation at GBs,whereas surface pores enable mechanical recovery via accelerated dislocation generation post-collapse.Additionally,size-dependent deformation regimes were identified,with 1 nm pores inducing negligible perturbation due to rapid atomic rearrangement,in contrast with persistent softening in 2.5 nm pores.These findings establish atomic-scale design principles for defect engineering in nickel-based aerospace components,demonstrating how crystallographic orientation,pore configuration,and GB interactions collectively govern nanoindentation behavior.展开更多
Achieving synergistic enhancement of damping-mechanical performance in pure Mg remains a tough challenge.Electric pulse treatment has proven effective in regulating the microstructure of materials.This work comprehens...Achieving synergistic enhancement of damping-mechanical performance in pure Mg remains a tough challenge.Electric pulse treatment has proven effective in regulating the microstructure of materials.This work comprehensively investigated the effects of pulse current on the microstructure and damping performance of pure Mg with micron-submicron grains,and revealed the mechanisms of damping enhancement associated with electric pulse treatment.The results suggest that pulse current effectively promotes dislocation disentanglement,thereby increasing the mobile dislocation density.In addition,pulse current facilitates dislocation slip and grain boundary relaxation in submicron samples,accompanied by the generation of high-density stacking faults.The microstructural evolution enhances the damping capacity of pure Mg.After electric pulse treatment,the strain amplitude independent damping(Q_(0)^(-1))in samples I-Q-0(7µm),I-Q-20(308 nm),and I-Q-60(155 nm)increased by 17%,11%,and 14%,while the strain amplitude dependent damping(Q_(h)^(-1))increased by 5%,11%,and 54%,respectively.The increment in strain amplitude independent damping capacityΔQ_(0)^(-1)is dominated by dislocations.Because pulse current can induce higher mobile dislocation density,contributing to greater energy dissipation and enhanced damping.Besides,the increment in strain amplitude dependent damping capacityΔQ_(h)^(-1)in micron I-Q-0(7µm)sample is also dominated by dislocation behavior.However,in submicron I-Q-20(308 nm)and I-Q-60(155 nm)samples,ΔQ_(h)^(-1)is dominated by stacking faults rather than dislocations.Consequently,damping and mechanical properties are synergistically improved in micron-submicron pure Mg by electric pulse treatment.展开更多
The development of novel quantum many-body computational algorithms relies on robust benchmarking.However,generating such benchmarks is often hindered by the massive computational resources required for exact diagonal...The development of novel quantum many-body computational algorithms relies on robust benchmarking.However,generating such benchmarks is often hindered by the massive computational resources required for exact diagonalization or quantum Monte Carlo simulations,particularly at finite temperatures.In this work,we propose a new algorithm for obtaining thermal pure quantum states,which allows efficient computation of both mechanical and thermodynamic properties at finite temperatures.We implement this algorithm in our open-source C++template library,Physica.Combining the improved algorithm with state-of-the-art software engineering,our implementation achieves high performance and numerical stability.As an example,we demonstrate that for the 4×4 Hubbard model,our method runs approximately 10~3times faster than HΦ3.5.2.Moreover,the accessible temperature range is extended down toβ=32 across arbitrary doping levels.These advances significantly push forward the frontiers of benchmarking for quantum many-body systems.展开更多
The scaling-up of electrochemical CO_(2)reduction requires circumventing the CO_(2)loss as carbonates under alkaline conditions.Zero-gap MEA cell configurations with a proton exchange membrane represent an alternative...The scaling-up of electrochemical CO_(2)reduction requires circumventing the CO_(2)loss as carbonates under alkaline conditions.Zero-gap MEA cell configurations with a proton exchange membrane represent an alternative solution in a pure acidic system,but the catalyst layer in direct contact with the hydrated proton environment usually leads to H_(2)evolution dominating.Herein,we show that polydimethyldiallyl-ammonium-chloride-coated Ag(Ag@PDDA)electrode exhibits outstanding performance with a FE of 86%,a single-pass conversion of 72%,and a stability of 28 h for CO production in pure-acid MEA compared with ammonium poly(N-methyl-piperidine-co-pterphenyl)decorated Ag(Ag/QAPPT)and cetyltrimethylammonium bromide decorated Ag(Ag/CTAB).The in situ ATR-SEIRAS reveal that PDDA creates a positive charge-rich protective outer layer and an N-rich hybrid inner layer,which not only suppresses the migration of H+during the electrolysis process and blocks the direct contact between H2O and Ag catalyst,but also promotes the generation from CO_(2)to*COOH in a pure-acid system.This work highlights the importance of polyelectrolyte engineering in regulating the electrocatalytic interface and accelerates the development of proton exchange membrane CO_(2)electrolysis.展开更多
基金The National Natural Science Foundation of China(Grant No.12462006)Beijing Institute of Structure and Environment Engineering Joint Innovation Fund(No.BQJJ202414).
文摘THE mechanical response and deformation mechanisms of pure nickel under nanoindentation were systematically investigated using molecular dynamics(MD)simulations,with a particular focus on the novel interplay between crystallographic orientation,grain boundary(GB)proximity,and pore characteristics(size/location).This study compares single-crystal nickel models along[100],[110],and[111]orientations with equiaxed polycrystalline models containing 0,1,and 2.5 nm pores in surface and subsurface configurations.Our results reveal that crystallographic anisotropy manifests as a 24.4%higher elastic modulus and 22.2%greater hardness in[111]-oriented single crystals compared to[100].Pore-GB synergistic effects are found to dominate the deformation behavior:2.5 nm subsurface pores reduce hardness by 25.2%through stress concentration and dislocation annihilation at GBs,whereas surface pores enable mechanical recovery via accelerated dislocation generation post-collapse.Additionally,size-dependent deformation regimes were identified,with 1 nm pores inducing negligible perturbation due to rapid atomic rearrangement,in contrast with persistent softening in 2.5 nm pores.These findings establish atomic-scale design principles for defect engineering in nickel-based aerospace components,demonstrating how crystallographic orientation,pore configuration,and GB interactions collectively govern nanoindentation behavior.
基金supported in part by the Guiding funds of central government for local scientific and technological development(YDZJSX2024C006)Natural Science Foundation of Shanxi Province(202203021221071)+1 种基金Research Project Supported by Shanxi Scholarship Council of China(2022-045)Project for Science and Technology Cooperation and Exchange of Shanxi Province(202404041101018).
文摘Achieving synergistic enhancement of damping-mechanical performance in pure Mg remains a tough challenge.Electric pulse treatment has proven effective in regulating the microstructure of materials.This work comprehensively investigated the effects of pulse current on the microstructure and damping performance of pure Mg with micron-submicron grains,and revealed the mechanisms of damping enhancement associated with electric pulse treatment.The results suggest that pulse current effectively promotes dislocation disentanglement,thereby increasing the mobile dislocation density.In addition,pulse current facilitates dislocation slip and grain boundary relaxation in submicron samples,accompanied by the generation of high-density stacking faults.The microstructural evolution enhances the damping capacity of pure Mg.After electric pulse treatment,the strain amplitude independent damping(Q_(0)^(-1))in samples I-Q-0(7µm),I-Q-20(308 nm),and I-Q-60(155 nm)increased by 17%,11%,and 14%,while the strain amplitude dependent damping(Q_(h)^(-1))increased by 5%,11%,and 54%,respectively.The increment in strain amplitude independent damping capacityΔQ_(0)^(-1)is dominated by dislocations.Because pulse current can induce higher mobile dislocation density,contributing to greater energy dissipation and enhanced damping.Besides,the increment in strain amplitude dependent damping capacityΔQ_(h)^(-1)in micron I-Q-0(7µm)sample is also dominated by dislocation behavior.However,in submicron I-Q-20(308 nm)and I-Q-60(155 nm)samples,ΔQ_(h)^(-1)is dominated by stacking faults rather than dislocations.Consequently,damping and mechanical properties are synergistically improved in micron-submicron pure Mg by electric pulse treatment.
基金Fu-Zhou Chen for helpful discussions.The work is partly supported by the National Key Research and Development Program of China(Grant No.2022YFA1402704)the National Natural Science Foundation of China(Grant No.12247101)。
文摘The development of novel quantum many-body computational algorithms relies on robust benchmarking.However,generating such benchmarks is often hindered by the massive computational resources required for exact diagonalization or quantum Monte Carlo simulations,particularly at finite temperatures.In this work,we propose a new algorithm for obtaining thermal pure quantum states,which allows efficient computation of both mechanical and thermodynamic properties at finite temperatures.We implement this algorithm in our open-source C++template library,Physica.Combining the improved algorithm with state-of-the-art software engineering,our implementation achieves high performance and numerical stability.As an example,we demonstrate that for the 4×4 Hubbard model,our method runs approximately 10~3times faster than HΦ3.5.2.Moreover,the accessible temperature range is extended down toβ=32 across arbitrary doping levels.These advances significantly push forward the frontiers of benchmarking for quantum many-body systems.
基金financial support of the National Natural Science Foundation of China(NSFC)(52394202,52021004,52301232,and 52476056)the Natural Science Foundation of Chongqing Province(2024NSCQ-MSX1109).
文摘The scaling-up of electrochemical CO_(2)reduction requires circumventing the CO_(2)loss as carbonates under alkaline conditions.Zero-gap MEA cell configurations with a proton exchange membrane represent an alternative solution in a pure acidic system,but the catalyst layer in direct contact with the hydrated proton environment usually leads to H_(2)evolution dominating.Herein,we show that polydimethyldiallyl-ammonium-chloride-coated Ag(Ag@PDDA)electrode exhibits outstanding performance with a FE of 86%,a single-pass conversion of 72%,and a stability of 28 h for CO production in pure-acid MEA compared with ammonium poly(N-methyl-piperidine-co-pterphenyl)decorated Ag(Ag/QAPPT)and cetyltrimethylammonium bromide decorated Ag(Ag/CTAB).The in situ ATR-SEIRAS reveal that PDDA creates a positive charge-rich protective outer layer and an N-rich hybrid inner layer,which not only suppresses the migration of H+during the electrolysis process and blocks the direct contact between H2O and Ag catalyst,but also promotes the generation from CO_(2)to*COOH in a pure-acid system.This work highlights the importance of polyelectrolyte engineering in regulating the electrocatalytic interface and accelerates the development of proton exchange membrane CO_(2)electrolysis.
