The multi-principal element characteristic of high-entropy alloys has revolutionized the conventional alloy design concept of single-principal element,endowing them with excellent mechanical properties.However,owing t...The multi-principal element characteristic of high-entropy alloys has revolutionized the conventional alloy design concept of single-principal element,endowing them with excellent mechanical properties.However,owing to this multi-principal element nature,high-entropy alloys exhibit complex deformation behavior dominated by alternating and coupled deformation mechanisms.Therefore,elucidating these intricate deformation mechanisms remains a key challenge in current research.Neutron diffraction(ND)techniques offer distinct advantages over traditional microscopic methods for characterizing such complex deformation behavior.The strong penetration capability of neutrons enables in-situ,real-time,and non-destructive detection of structural evolution in most centimeter-level bulk samples under complex environments,and ND allows precise characterization of lattice site occupations for light elements,such as C and O,and neighboring elements.This review discussed the principles of ND,experiment procedures,and data analysis.Combining with recent advances in the research about face-centered cubic high-entropy alloy,typical examples of using ND to investigate the deformation behavior were summarized,ultimately revealing deformation mechanisms dominated by dislocations,stacking faults,twinning,and phase transformations.展开更多
This study investigates the plastic deformation behaviour of the AZ31 magnesium alloy under various uniaxial loading conditions using in-situ neutron diffraction,the crystallite group method(CGM),and crystal plasticit...This study investigates the plastic deformation behaviour of the AZ31 magnesium alloy under various uniaxial loading conditions using in-situ neutron diffraction,the crystallite group method(CGM),and crystal plasticity modelling.A key novelty of this work is the direct,model independent determination of resolved shear stress(RSS)values for individual slip and twinning systems,as well as their critical values(CRSS),derived from lattice strains in grains with preferred orientations.The experiment was extended beyond the conventional loading paths along the normal direction(ND)and rolling direction(RD)to include compression at angles of 30°and 60°from the ND(referred to as NDC30 and NDC60 tests),which had not been investigated in previous studies.Notably,the NDC30 test,combined with diffraction measurements,was specifically designed to activate basal slip in the majority of grains while minimizing twinning,enabling clear identification of this slip system and accurate determination of its CRSS.For the first time,hardening parameters were determined by comparing the model predicted values of RSS with those obtained from diffraction measurements for each active system.These data,together with the results of macroscopic tests,were used to calibrate an elastic-plastic self-consistent(EPSC)model,which accurately reproduced stress partitioning under applied load,texture evolution,and twin activity.The integrated methodology enhances the reliability of CRSS input and improves the modelling of anisotropic plasticity in magnesium alloys by tuning intergranular interactions based on a modified Eshelby inclusion approach.展开更多
为提高管道环焊缝超声衍射时差法(time of flight diffraction,TOFD)扫描图谱在背景信号干扰、样本量不均衡等情况下的缺陷识别效果,提出了一种改进的YOLOv5s网络模型.针对管道环焊缝TOFD图谱中缺陷形态不规则的特点,通过引入可变形卷积...为提高管道环焊缝超声衍射时差法(time of flight diffraction,TOFD)扫描图谱在背景信号干扰、样本量不均衡等情况下的缺陷识别效果,提出了一种改进的YOLOv5s网络模型.针对管道环焊缝TOFD图谱中缺陷形态不规则的特点,通过引入可变形卷积,使得网络自适应缺陷自身的形状特点,提高TOFD图谱中不规则缺陷的特征提取能力;针对TOFD扫描图谱中直通波和底面波等干扰波形对缺陷识别的影响,通过在网络不同深度分别添加自注意力机制,引导网络关注缺陷细微特征的同时抑制界面波对缺陷识别的影响;针对实际样本中各类缺陷不均衡的情况,采用SlideLoss损失函数代替原损失函数,提高网络对样本量较少的裂纹类缺陷的识别精度.对比试验结果表明,改进后的网络能够抑制TOFD图谱复杂背景干扰,提高样本不均衡条件下的识别率.相比原网络,整体平均识别率均值(mean Average Precision,mAP)和裂纹类缺陷的平均识别率(Average Precision,AP)分别提高了8.2%和7.3%.展开更多
基金National Key R&D Program of China(2023YFB3711904,2022YFA1603801)National Natural Science Foundation of China(12404230,52471181,52301213,52130108,52471005)+2 种基金National Nature Science Foundation of Zhejiang Province(LY23E010002)Open Fund of the China Spallation Neutron Source,Songshan Lake Science City(KFKT2023B11)Guangdong Basic and Applied Basic Research Foundation(2022A1515110805,2024A1515010878)。
文摘The multi-principal element characteristic of high-entropy alloys has revolutionized the conventional alloy design concept of single-principal element,endowing them with excellent mechanical properties.However,owing to this multi-principal element nature,high-entropy alloys exhibit complex deformation behavior dominated by alternating and coupled deformation mechanisms.Therefore,elucidating these intricate deformation mechanisms remains a key challenge in current research.Neutron diffraction(ND)techniques offer distinct advantages over traditional microscopic methods for characterizing such complex deformation behavior.The strong penetration capability of neutrons enables in-situ,real-time,and non-destructive detection of structural evolution in most centimeter-level bulk samples under complex environments,and ND allows precise characterization of lattice site occupations for light elements,such as C and O,and neighboring elements.This review discussed the principles of ND,experiment procedures,and data analysis.Combining with recent advances in the research about face-centered cubic high-entropy alloy,typical examples of using ND to investigate the deformation behavior were summarized,ultimately revealing deformation mechanisms dominated by dislocations,stacking faults,twinning,and phase transformations.
基金founded by the National Science Centre,Poland(NCN),under grant no.UMO-2023/49/B/ST11/00774The research(neutron diffraction experiments)leading to this result has been co-funded by the project NEPHEWS under grant agreement no.101131414 from the EU Framework Programme for Research and Innovation Horizon Europe+6 种基金Views and opinions expressed are however those of the author(s)only and do not necessarily reflect those of the European Union.Neither the European Union nor the granting authorities can be held responsible for them.Measurements were carried out at the CANAM infrastructure of the NPI CAS Rez.The employment of the CICRR infrastructure supported by MEYS project LM2023041 is acknowledgedThe Ministry of Education,Youth and Sports of the Czech Republic(MEYS),support of large research infrastructures LM2023057K.M.acknowledges support of the Czech Grant Agency under project no.25-16210SP.K.acknowledges support from the European Union's Horizon 2020 research and innovation program under the NOMATEN teaming grant agreement no.857470the European Regional Development Fund via the Foundation for Polish Science International Research Agenda Plus Program grant no.MAB PLUS/2018/8the Ministry of Science and Higher Education's initiative“Support for the Activities of Centers of Excellence Established in Poland under the Horizon 2020 Program”under agreement no.MEiN/2023/DIR/3795K.W.was partly supported by the program“Excellence initiative-research university”for the AGH University of Krakow.
文摘This study investigates the plastic deformation behaviour of the AZ31 magnesium alloy under various uniaxial loading conditions using in-situ neutron diffraction,the crystallite group method(CGM),and crystal plasticity modelling.A key novelty of this work is the direct,model independent determination of resolved shear stress(RSS)values for individual slip and twinning systems,as well as their critical values(CRSS),derived from lattice strains in grains with preferred orientations.The experiment was extended beyond the conventional loading paths along the normal direction(ND)and rolling direction(RD)to include compression at angles of 30°and 60°from the ND(referred to as NDC30 and NDC60 tests),which had not been investigated in previous studies.Notably,the NDC30 test,combined with diffraction measurements,was specifically designed to activate basal slip in the majority of grains while minimizing twinning,enabling clear identification of this slip system and accurate determination of its CRSS.For the first time,hardening parameters were determined by comparing the model predicted values of RSS with those obtained from diffraction measurements for each active system.These data,together with the results of macroscopic tests,were used to calibrate an elastic-plastic self-consistent(EPSC)model,which accurately reproduced stress partitioning under applied load,texture evolution,and twin activity.The integrated methodology enhances the reliability of CRSS input and improves the modelling of anisotropic plasticity in magnesium alloys by tuning intergranular interactions based on a modified Eshelby inclusion approach.
文摘为提高管道环焊缝超声衍射时差法(time of flight diffraction,TOFD)扫描图谱在背景信号干扰、样本量不均衡等情况下的缺陷识别效果,提出了一种改进的YOLOv5s网络模型.针对管道环焊缝TOFD图谱中缺陷形态不规则的特点,通过引入可变形卷积,使得网络自适应缺陷自身的形状特点,提高TOFD图谱中不规则缺陷的特征提取能力;针对TOFD扫描图谱中直通波和底面波等干扰波形对缺陷识别的影响,通过在网络不同深度分别添加自注意力机制,引导网络关注缺陷细微特征的同时抑制界面波对缺陷识别的影响;针对实际样本中各类缺陷不均衡的情况,采用SlideLoss损失函数代替原损失函数,提高网络对样本量较少的裂纹类缺陷的识别精度.对比试验结果表明,改进后的网络能够抑制TOFD图谱复杂背景干扰,提高样本不均衡条件下的识别率.相比原网络,整体平均识别率均值(mean Average Precision,mAP)和裂纹类缺陷的平均识别率(Average Precision,AP)分别提高了8.2%和7.3%.
