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| 1 | Origin of strong solid solution strengthening in the CrCoNi-W medium entropy alloy显示文摘Solid solution strengthening is one of the most conventional strategies for optimizing alloys strength,while the corresponding mechanisms can be more complicated than we traditionally thought specifically as heterogeneity of microstructure is involved.In this work,by comparing the change of chemical distribution,dislocation behaviors and mechanical properties after doping equivalent amount of tungsten(W)atoms in CrCoNi alloy and pure Ni,respectively,it is found that the alloying element W in CrCoNi alloy resulted in much stronger strengthening effect due to the significant increase of heterogeneity in chemical distribution after doping trace amount of W.The large atomic scale concentration fluctuation of all elements in CrCoNi-3W causes dislocation motion via strong nanoscale segment detrapping and severe dislocation pile up which is not the case in Ni-3W.The results revealed the high sensitivity of elements distribution in multi-principle element alloys to composition and the significant consequent influence in tuning the mechanical properties,giving insight for complex alloy design. | Yujie Chen Yan Fang Xiaoqian Fu Yiping Lu Sijing Chen Hongbin Bei Qian Yu | 2021 | Journal of Materials Science & Technology2021，，14： | 5 |
| 2 | Strengthening in Al-,Mo-or Ti-doped CoCrFeNi high entropy alloys:A parallel comparison显示文摘In the current work,a parallel comparison of the influence of Al,Mo and Ti,on the microstructure and strengthening of the CoCrFeNi alloy was conducted.To achieve this,inconsistencies on variables including the extent of alloying,thermomechanical processing and property-evaluation method were avoided.Microstructurally,following cold-rolling,annealing of the 4 at.%Al-doped alloys at 800-1000℃ did not result in phase separation;nevertheless,that of the 4 at.%Mo-and Ti-doped alloys led to the respective formation ofσandηphase and,consequently,caused extra strengthening through the Orowan dislocation bypassing mechanism.Our systematic qualitative analysis and DFT calculations showed that Al and Ti are more effective than Mo in reducing the stacking fault energy(SFE)of the CoCrFeNi alloy,because they can induce more considerable deformation of electronic density,making the gliding of atomic layers easier.Following identical thermomechnical processing,Al-,Mo-,and Ti-doping causes different extent of solid solution strengthening and grain boundary strengthening.Mo causes the most pronounced solid solution strengthening but does not benefit the grain boundary strengthening;in contrast,the effectiveness of grain boundary strengthening is boosted by the doping Al and Ti.Current analyses support that Labusch instead of Fleischer mechanism is applicable to explain the differences in solid solution strengthening,and the observed differences in grain boundary strengthening arise from the different tendency of Al,Mo and Ti to reduce the SFE of CoCrFeNi.In addition,we determined the value of the dimensionless parameter f in the Labusch model for CoCrFeNi-based alloys and observed a close relation between Hall-Petch slope and SFE.Although more in-depth studies are needed to provide full and mechanistic understandings,both these findings in fact presents significant values toward designing novel singlephase high-strength CoCrFeNi-based alloys through manipulating the solid solution and grain boundary strengthening by compositional tuning. | Xi Li Zhongtao Li Zhenggang Wu Shijun Zhao Weidong Zhang Hongbin Bei Yanfei Gao | 2021 | Journal of Materials Science & Technology2021，，35： | 4 |
| 3 | Inconsistent creep between dendrite core and interdendritic region under different degrees of elemental inhomogeneity in nickel-based single crystal superalloys显示文摘The creep inconsistency between dendrite core and interdendritic region is investigated in a nickel-based single crystal superalloy under 1373 K and 137 MPa.Two specimens with higher and lower degree of elemental inhomogeneity on dendritic structures are compared.For specimen with higher inhomogeneity,stronger segregation of refractory elements reinforces the local strength in dendrite core,but damages the strength in interdendritic region.Creep strain is accumulated faster in interdendritic region giving rise to promoted dislocation shearing inγphase,faster degradation of dislocation networks and facilitated topological inversion of rated structures.Although the segregation of refractory elements produces a high density of topologically close-packed(TCP)phase in dendrite core,faster accumulation of creep strain forms microcracks prior in interdendritic region that gives rise to final rupture of the specimen.In another specimen,increased solid solution time gives rise to overall reduced inhomogeneity.Creep inconsistency is relieved to show more uniform evolution of dislocation substructures and rafting between dendrite core and interdendritic region.The second specimen is ruptured by formation and extension of microcracks along TCP phase although the precipitation of TCP phase is relatively restricted under reduced inhomogeneity.Importantly,the balance of local strength between dendrite core and interdendritic region results in over 40%increase of creep rupture life of the second specimen. | Wanshun Xia Xinbao Zhao Liang Yue Quanzhao Yue Jiangwei Wang Qingqing Ding Hongbin Bei Ze Zhang | 2021 | Journal of Materials Science & Technology2021，，33： | 2 |
| 4 | Discrete twinning dynamics and size-dependent dislocation-to twin transition in body-centred cubic tungsten显示文摘Body-centred cubic(BCC) metals are known to have unstable intrinsic stacking faults and high resistance to deformation twinning, which can strongly influence their twinning behaviour. Though twinning mechanisms of BCC metals have been investigated for more than 60 years, the atomistic level dynamics of twinning remains under debate, especially regarding its impact on competition between twinning and slip. Here, we investigate the atomistic level dynamics of twinning in BCC tungsten(W) nanowires using in situ nanomechanical testing. Quantitative experimental studies directly visualize that deformation twins in W nanowires have a minimum size of six-layers and grow in increments of approximately three-layers at a time, in contrast to the layer-by-layer growth of deformation twins in face-centred cubic metals. These unique twinning dynamics induces a strong competition with ordinary dislocation slip,as exhibited by a size-dependent dislocation-to-twin transition in W nanowires, with a transition size of ~40 nm. Our work provides physical insight into the dynamics of twinning at the atomic level, as well as a size-dependent dislocation-twinning competition, which have important implications for the plastic deformation in a broad class of BCC metals and alloys. | Jiangwei Wang Anik H.M.Faisal Xiyao Li Youran Hong Qi Zhu Hongbin Bei Ze Zhang Scott X Mao Christopher R.Weinberger | 2022 | Journal of Materials Science & Technology2022，，11： | 2 |
| 5 | Studies on the corrosion behavior of yttrium-implanted zircaloy-4显示文摘 | Jian Xu Xinde Bai Yudian Fan Wenliang Liu Hongbin Bei | 2000 | Journal of Materials Science2000，，24： | 1 |
| 6 | Studies on the corrosion behavior of yttrium-implanted zircaloy-4显示文摘 | Jian Xu Xinde Bai Yudian Fan Wenliang Liu Hongbin Bei | 2000 | Journal of Materials Science2000，，24： | 1 |
| 7 | Unfolding the complexity of phonon quasi-particle physics in disordered materials显示文摘The concept of quasi-particles forms the theoretical basis of our microscopic understanding of emergent phenomena associated with quantum-mechanical many-body interactions.However,the quasi-particle theory in disordered materials has proven difficult,resulting in the predominance of mean-field solutions.Here,we report first-principles phonon calculations and inelastic X-ray and neutron-scattering measurements on equiatomic alloys(NiCo,NiFe,AgPd,and NiFeCo)with force-constant dominant disorder—confronting a key 50-year-old assumption in the Hamiltonian of all mean-field quasi-particle solutions for off-diagonal disorder.Our results have revealed the presence of a large,and heretofore unrecognized,impact of local chemical environments on the distribution of the species-pair-resolved force-constant disorder that can dominate phonon scattering.This discovery not only identifies a critical analysis issue that has broad implications for other elementary excitations,such as magnons and skyrmions in magnetic alloys,but also provides an important tool for the design of materials with ultralow thermal conductivities. | Sai Mu Raina J.Olsen Biswanath Dutta Lucas Lindsay German D.Samolyuk Tom Berlijn Eliot D.Specht Ke Jin Hongbin Bei Tilmann Hickel Bennet C.Larson George M.Stocks | 2020 | npj Computational Materials2020，，1： | 0 |
| 8 | The dependence of stress and strain rate on the deformation behavior of a Ni‐based single crystal superalloy at 1050°C显示文摘Ni‐based single crystal(SX)superalloys are important high‐temperature materials used for manufacturing turbine blades in aero‐engines.During service under combinational impacts of temperature and stress,the SX superalloy may reach its life due to plastic deformation,which normally accompanies time‐dependent microstructural degradation.To reveal this dynamically mechanical response,tensile tests at 1050°C are carried out to record stress‐strain curves at five stain rates as well as creep curves at four applied stresses.Deformed microstructures and defects have been analyzed to understand mechanical behaviors and the underlying mechanism by using advanced scanning electron and scanning transmission electron microscopes.Results show that the de-formation mode of the alloy strongly depends on the strain rates/applied stresses under mechanical loading.The dislocation density inside theγphase is extremely low at all tests,indicating that theγphase is relatively weak and ready to flow at this temperature even at a very fast strain rate.The deformation behavior of theγ′phase is much complicated.At fast strain rates or high applied stresses,the dislocation density in theγ′phase is very high,contributing to high‐stress requirements to deform the material.At slow strain rates or low applied stresses,rafting microstructures develop and the de-formation mode becomes directional coarsening/diffusion‐dominated.Our results de-monstrate a comprehensive understanding of the deformation mechanism of Ni‐based SX superalloys,which may provide lifetime prediction of the mechanical fail-ure,as well as the database for superalloy applications in mechanical systems. | Qingqing Ding Hongbin Bei Lulu Li Jie Ouyang Xinbao Zhao Xiao Wei Ze Zhang | 2021 | International Journal of Mechanical System Dynamics2021，1，1： | 0 |
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