| 1 | Designing hetero-structured ultra-strong and ductile Zr-2.5Nb alloys:Utilizing the grain size-dependent martensite transformation during quenching显示文摘To further improve the service performance of Zr-2.5Nb alloy worked as pressure tubes in pressurized heavy water reactors,more investigation about the microstructure and thermomechanical processing route of Zr-2.5Nb alloy need to be conducted.In this work,a hetero-structured Zr-2.5Nb alloy was prepared by applying a novel technique.Microstructure analysis reveals that the alloy exhibits a grain sizedependent martensite substructure transition during post-rolling quenching.The hetero-structure consists of equiaxed primaryαgrains and the lamellae groups containing both parallelα’dislocation martensite andα’twin martensite.Compared with the previously reported Zr-Nb alloys,the present Zr-2.5Nb alloys manifest the highest yield strength(∼710 MPa),together with a high ultimate tensile strength(∼844 MPa)and good ductility(∼17.1%).The enhanced mechanical properties are found to arise from the properly controlled fraction/size of the two types of martensite,which not only significantly strengthens the alloy but also contributes to a stronger strain hardening.A model based on the grain-size-dependent critical resolved shear stress for dislocation slip and twinning has been proposed to explain theα’martensite substructures transition at a critical grain size dc=3.3μm.Below this size,the critical resolved shear stress(CRSS)for twinning is higher than that for theslip.Thus,theα’dislocation martensite is more favorable to form.Otherwise,theα’twin martensite would exhibit a high activity.The present work indicates that making use of the grain size-dependent martensite transformation to tailor the heterostructure in Zr alloys is an effective strategy to overcome the strength–ductility trade-off in the material. | S.Y.Liu J.Y.Zhang J.Kuang X.Y.Bao D.D.Zhang C.L.Zhang J.K.Yang G.Liu J.Sun | 2022 | Journal of Materials Science & Technology2022，，30： | 0 |
| 2 | The spatial evolution of velocity and density profiles in an arrested salt wedge显示文摘The spatial variation in the properties of an arrested salt wedge have been investigated,both analytically and in the laboratory.In the laboratory particle image velocimetry and laser induced fluorescence were used to obtain flow velocities and the height of the density interface.An analytical solution for the profile of interface height,in the absence of interfacial instabilities,has been developed from two-layer internal hydraulic theory.The evolution of the velocity profile is predicted using a momentum diffusion equation following a Lagrangian frame of reference along the interface of the salt wedge.The centre of the shear layer is predicted to lie above the density interface,with this offset decreasing in the downstream direction.Our theoretical predictions are in good agreement with our laboratory measurements. | Adam J.K.Yang E.W.Tedford G.A.Lawrence | 2019 | Theoretical & Applied Mechanics Letters2019，9，6： | 0 |
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