With the development of new materials and technology,high entropy alloy(HEA)nitride films have attracted much attention of researchers due to their excellent optical properties and mechanical properties.Herein,a novel...With the development of new materials and technology,high entropy alloy(HEA)nitride films have attracted much attention of researchers due to their excellent optical properties and mechanical properties.Herein,a novel SS/NbMoTaWN(HEAN)/NbMoTaWON(HEAON)/SiO_(2) coatings are prepared,which shows a high spectral selectivity of a/ε=0.944/0.12.The preparation and optimization of the coating are studied by combining experiments with ellipsometric program and CODE software.High temperature thermal stability test is performed in depth,which proves that the coating could bear 400℃ in air for 2 h,and 600℃for 2 h in vacuum.Long-term thermal stability researches indicate that the SSACs still keep good optical properties(a=0.902,ε=0.106)even after annealing at 600℃ for 100 h.The failure mechanism is analyzed by XRD and Raman spectra.In addition,neutral salt spray test is performed to investigate the anti-corrosion ability,which indicates the coating has a good optical performance after soaking in 3.5 wt%NaCl solution for 30 days.Obviously,this work provides a new strategy to construct solar absorber coatings based on NbMoTaW high entropy alloy.展开更多
Transition metal nitrides(TMNs)have gained widespread application in protecting structural components due to their high strength and hardness.However,TMNs still have the challenge of structural instability and mechani...Transition metal nitrides(TMNs)have gained widespread application in protecting structural components due to their high strength and hardness.However,TMNs still have the challenge of structural instability and mechanical deterioration caused by oxidation under harsh high temperature conditions.Herein,we present a strategy combining component regulation with high-entropy engineering to develop an advanced high-temperature Al-containing high-entropy nitrides(HENs)material.To prevent the phase decomposition of AlN within the(NbMoTaWAl)N,theoretical simulations were employed to determine a critical atomic percent of 25.0%Al for maintaining the stability of the high-entropy structure.Ensuing experimental synthesis creates three NbeMoeTaeWeAleN films with varying Al content:a high-entropy film with 0.0%Al(HEN),a high-entropy film with 21.2%Al(HEN-Al),and an amorphous transition metal nitride film with 30.2%Al(a-TMN-Al),validating key high-entropy engineering benchmarks.It is found that the unique HEN-Al film exhibits excellent oxidation resistance and hightemperature hardness,attributed to the uniform distribution of Al atoms in the robust high-entropy structure,which creates conditions for forming a dense and continuous Al_(2)O_(3) barrier layer,effectively hindering the diffusion of oxygen into the film interior.This study provides new insights to develop a new generation of high-temperature protective materials.展开更多
The striking variation in damage tolerance among refractory complex concentrated alloys is examined through the analysis of atomistic fracture simulations,contrasting behavior in elemental Nb with that in brittle NbMo...The striking variation in damage tolerance among refractory complex concentrated alloys is examined through the analysis of atomistic fracture simulations,contrasting behavior in elemental Nb with that in brittle NbMoTaW and ductile Nb_(45)Ta_(25)Ti_(15)Hf_(15).We employ machine-learning interatomic potentials(MLIPs),including a new MLIP developed for NbTaTiHf,in atomistic simulations of crack tip extension mechanisms based on analyses of atomistic fracture resistance curves.While the initial behavior of sharp cracks shows good correspondence with the Rice theory,fracture resistance curves reveal marked changes in fracture modes for the complex alloys as crack extension proceeds.In NbMoTaW,compositional complexity appears to promote dislocation nucleation relative to pure Nb,despite theoretical predictions that the alloy should be relatively more brittle.In Nb_(45)Ta_(25)Ti_(15)Hf_(15),alloying alters the fracture mode compared to elemental Nb,promoting crack tip blunting and enhancing resistance to crack propagation.展开更多
基金This workwas financially supported by the regional key projects of science and technology service network program of Chinese Academy of Sciences(KFJ-STS-QYZD-139)the Youth Innovation Promotion Association CAS(2018455)the Major Science and Technology Projects of Gansu Province(20ZD7GF011).
文摘With the development of new materials and technology,high entropy alloy(HEA)nitride films have attracted much attention of researchers due to their excellent optical properties and mechanical properties.Herein,a novel SS/NbMoTaWN(HEAN)/NbMoTaWON(HEAON)/SiO_(2) coatings are prepared,which shows a high spectral selectivity of a/ε=0.944/0.12.The preparation and optimization of the coating are studied by combining experiments with ellipsometric program and CODE software.High temperature thermal stability test is performed in depth,which proves that the coating could bear 400℃ in air for 2 h,and 600℃for 2 h in vacuum.Long-term thermal stability researches indicate that the SSACs still keep good optical properties(a=0.902,ε=0.106)even after annealing at 600℃ for 100 h.The failure mechanism is analyzed by XRD and Raman spectra.In addition,neutral salt spray test is performed to investigate the anti-corrosion ability,which indicates the coating has a good optical performance after soaking in 3.5 wt%NaCl solution for 30 days.Obviously,this work provides a new strategy to construct solar absorber coatings based on NbMoTaW high entropy alloy.
基金supported by the National Natural Science Foundation of China(Grant Nos.52322206,51972139)the Science and Technology Development Program of Jilin province(Grant No.20210101062JC)+1 种基金funded by the National Key R&D Program of China(2023YFF0716800)the High-Performance Computing Center of Jilin University,China.
文摘Transition metal nitrides(TMNs)have gained widespread application in protecting structural components due to their high strength and hardness.However,TMNs still have the challenge of structural instability and mechanical deterioration caused by oxidation under harsh high temperature conditions.Herein,we present a strategy combining component regulation with high-entropy engineering to develop an advanced high-temperature Al-containing high-entropy nitrides(HENs)material.To prevent the phase decomposition of AlN within the(NbMoTaWAl)N,theoretical simulations were employed to determine a critical atomic percent of 25.0%Al for maintaining the stability of the high-entropy structure.Ensuing experimental synthesis creates three NbeMoeTaeWeAleN films with varying Al content:a high-entropy film with 0.0%Al(HEN),a high-entropy film with 21.2%Al(HEN-Al),and an amorphous transition metal nitride film with 30.2%Al(a-TMN-Al),validating key high-entropy engineering benchmarks.It is found that the unique HEN-Al film exhibits excellent oxidation resistance and hightemperature hardness,attributed to the uniform distribution of Al atoms in the robust high-entropy structure,which creates conditions for forming a dense and continuous Al_(2)O_(3) barrier layer,effectively hindering the diffusion of oxygen into the film interior.This study provides new insights to develop a new generation of high-temperature protective materials.
基金supported by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences,Materials Sciences and Engineering Division,under Contract No.DE-AC02-05-CH11231 within the Damage Tolerance in Structural Materials(KC 13)programThe study made use of resources of the National Energy Research Scientific Computing Center(NERSC),a U.S.Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory,operated under the same contract number,using NERSC Award No.BES-ERCAP0027535This research used the Lawrencium computational cluster resource provided by the IT Division at the Lawrence Berkeley National Laboratory(Supported by the Director,Office of Science,Office of Basic Energy Sciences,of the U.S.Department of Energy under Contract No.DE-AC02-05CH11231).The Scientific Computing Group(also known as High-Performance Computing Services)under Science IT supports the mission of Lawrence Berkeley National Laboratory by providing technology and consulting support for science and technical programs,in the areas of data management,HPC cluster computing,and Cloud services.
文摘The striking variation in damage tolerance among refractory complex concentrated alloys is examined through the analysis of atomistic fracture simulations,contrasting behavior in elemental Nb with that in brittle NbMoTaW and ductile Nb_(45)Ta_(25)Ti_(15)Hf_(15).We employ machine-learning interatomic potentials(MLIPs),including a new MLIP developed for NbTaTiHf,in atomistic simulations of crack tip extension mechanisms based on analyses of atomistic fracture resistance curves.While the initial behavior of sharp cracks shows good correspondence with the Rice theory,fracture resistance curves reveal marked changes in fracture modes for the complex alloys as crack extension proceeds.In NbMoTaW,compositional complexity appears to promote dislocation nucleation relative to pure Nb,despite theoretical predictions that the alloy should be relatively more brittle.In Nb_(45)Ta_(25)Ti_(15)Hf_(15),alloying alters the fracture mode compared to elemental Nb,promoting crack tip blunting and enhancing resistance to crack propagation.
