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Precipitation process and its effects on properties of aging Cu–Ni–Be alloy

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Rare Metals 2013年第4期32卷 332-337页

作者： Li-Jun Peng Bai-Qing Xiong Guo-Liang Xie Qiang-Song Wang Song-Bai Hong State Key Laboratory of Nonferrous Metals & Process General Research Institute for Nonferrous Metals Yingtan Shine Electric Metal Material Co. Ltd

The precipitation process of aged Cu-Ni-Be alloy was investigated by X-ray diffraction （XRD）, trans- mission electron microscopy （TEM）, and high-resolution transmission electron microscopy （HRTEM）. The tensile strength, yield strength, and electronic conductivity of this alloy after aging were also studied. The precipitation sequence of the C17510 alloy aged at 525 ℃ is supersat-urated solid solution→G.P zones→ γ″-γ′→ γ. This transformation can be achieved by the accumulation of Be-atom layers. The G.P zones are composed of disk-shaped monolayers of Be atoms, which are formed on （001） matrix planes. The intermediate γ″ precipitate is nucleated in the G.P zones. The γ″ and γ′ precipitates have the same orientation relationship with matrix, e.g., （110）p｜｜（100）M,[001]p｜｜[001]M. The tensile strength of specimen shows a maximum during the aging process and then continuously decreases if the specimen is over aged. The strengthening effect of γ′ phase precipitated in aging at 525 ℃ for 4 h is calculated to be 436 MPa according to the Orowan strengthening, which is quite consistent with the experimental data.

关键词： Precipitation process C17510 alloy metastable phases Strengthening mechanism

A Novel Multiphase Stainless Steel with Ultra-Low Yield Ratio and High Ductility

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Acta Metallurgica Sinica(English Letters) 2024年第10期37卷 1777-1784页

作者： Menghao Liu Cuiwei Du Yuewu Li Xiaogang Li Beijing Advanced Innovation Center for Materials Genome Engineering Institute for Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijing100083China National Materials Corrosion and Protection Data Center University of Science and Technology BeijingBeijing100083China

This study focuses on developing a novel multiphase stainless steel with enhanced ductility and an ultralow yield ratio achieved through solid-solution *** steel exhibits remarkable mechanical properties:a tensile strength of approximately 1114 MPa,an ultralow yield ratio of 0.36,exceptional uniform elongation of approximately 17.48%,and total elongation of approximately 21.73%.The remarkable ductility of the steel can be attributed to the transformation-induced plasticity(TRIP)effect observed in the retained austenite,while its exceptional strength results from the combined effects of TRIP and the martensite phase.

关键词： Stainless steels metastable phases Low yield ratio Martensitic phase transformation

Insights into the nucleation,grain growth and phase transformation behaviours of sputtered metastableβ-W films

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Journal of Materials Science & Technology 2021年第31期90卷 66-75页

作者： Shuqun Chen Jinshu Wang Ronghai Wu Zheng Wang Yangzhong Li Yiwen Lu Wenyuan Zhou Peng Hua Hongyi Lia Key Laboratory of Advanced Functional Materials Education Ministry of ChinaFaculty of Materials and ManufacturingBeijing University of TechnologyBeijing 100124China School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an 710129China High Performance Computing Department National Supercomputing Center in ShenzhenShenzhen 518055China China Ship Development and Design Center Wuhan 430074China

metastable phase in tungsten film is of great interests in recent years due to its giant spin Hall effects,however,little information has been known on its nucleation,growth and phase *** this paper,a 900 nm-thick tungsten film with double-layer structure(α-W underlayer andβ-W above it)was produced on SiO_(2)/Si substrate by high vacuum magnetron sputtering at room *** structural properties ofβ-W were systemically investigated by X-ray diffraction,transmission electron microscopy,thermodynamic calculation,first-principle and phase-field *** is found that theβ-W nucleation is energetically favoured on the SiO_(2)surface compared to theα-W *** the film thickening proceeds,β-W[211]turns to be preferred direction of growth owing to the elastic strain energy minimization,which is verified by phase-field ***,theβ→αphase transformation takes place near the film-substrate interface while the rest of the film keeps theβ-W phase,leading to a doublelayer *** localized phase transition is induced by lower Gibbs free energy ofα-W phase at larger grain sizes,which can be confirmed by thermodynamic *** in-situ heating TEM analysis of the as-deposited film reveals that theβ→αphase transformation is fulfilled byα/βinterface propagation rather than local atomic *** findings offer valuable insights into the intrinsic properties of metastable phase in tungsten.

关键词： metastable phases Tungsten Nucleation and growth Phase field modelling Phase transformation

Accelerated exploration of TRIP metallic glass composite by laser additive manufacturing

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Journal of Materials Science & Technology 2021年第19期78卷 68-73页

作者： Zejiang Yu Wei Zheng Zhiqiang Li Yunzhuo Lu Xinbing Yun Zuoxiang Qin Xing Lu School of Materials Science and Engineering Dalian Jiaotong UniversityDalian 116028China Xi'an Space Engine Company Limited Xi'an710100China Engineering Research Center of Continuous Extrusion Ministry of EducationDalian Jiaotong UniversityDalian116028China

Introducing transformation-induced plasticity(TRIP)effect into bulk metallic glass composites(BMGCs)is an effective route to improve their ductility and strain-hardening *** the morphology and structure of the crystalline austenite phases responsible for the TRIP phenomenon are strongly dependent on the alloy composition and cooling rate during freezing,distinguishing the optimal cases from a vast variety of candidates is the primary task of exploring TRIP ***,without a suitable theoretical guidance,the exploration of BMGCs is usually performed via the traditional trial-and-error route,making the BMGC development extremely time consuming and labor ***,we present a novel high-throughput strategy to accelerate the exploration process of TRIP *** efficiency of this strategy was demonstrated on a well-studied Cu-Zr-Al alloy system.A screening library,comprised by121 cylindrical samples with different conditions,was rapidly prepared by laser additive manufacturing(LAM).The phases of the library were efficiently identified by micro-area X-ray diffraction(M-XRD)to screen the optimal compositions and cooling rates that precipitate only B2-Cu Zr *** distribution uniformity of the B2-Cu Zr phase was further evaluated based on digital image processing technology to screen the candidates of better *** high-throughput results are in good agreement with the previous casting investigations of discrete samples,confirming the validity of the present high-throughput strategy.

关键词： Bulk amorphous materials Composites High-throughput Laser deposition metastable phases

In situ scanning electron microscopy observation of deformation and fracture behavior of Ti-3Zr-2Sn-3Mo-25Nb alloy

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Rare Metals 2012年第4期31卷 318-322页

作者： Ma, Xiqun Yu, Zhentao Han, Yong Song, Xiping Sun, Qiaoyan Northwest Institute for Nonferrous Metal Research Xi'an 710016China State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong UniversityXi'an 710049China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeiiing 100083China

The plastic deformation and fracture processes of Ti-3Zr-2Sn-3Mo-25Nb alloy for surgical implants were directly observed by in situ scanning electron microscopy(SEM).The effect of phase transformations on deformation-induced martensitic transformation accompanying the cyclic tensile fracture processes was *** results reveal that the metastable alpha martensites(α″) promotes deformation-induced martensitic transformation to ductile fracture,whereas the omega(ω) and alpha(α) phases drastically prevent slip dislocation and deformation-induced martensitic transformation to brittle fracture.

关键词： titanium alloys metastable phases martensitic phase transformation deformation

Metastability effects in strained and stressed SrTiO_(3) films

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Journal of Advanced Dielectrics 2016年第3期6卷 5-16页

作者： Alexander I.Lebedev Physics Department Moscow State University Leninskie GoryMoscow 119991Russia

The sequence of ground states for SrTiO_(3) film subjected to epitaxial strain as well as to mechanical stress along the[001]and[110]axes is calculated from first principles within the density functional *** the fixed-strain boundary conditions,an increase in the lattice parameter of a substrate results in the I4cm→I4/mcm→Ima2→Cm→Fmm2→Ima2(II)sequence of ground *** the fixed-stress boundary conditions,the phase sequence is different and depends on how the stress is *** is revealed that the simultaneous presence of competing ferroelectric and antiferrodistortive instabilities in SrTiO_(3) gives rise to the appearance of metastable phases,whose number increases dramatically under the fixed-stress *** the metastable phases,the octahedral rotation patterns are shown to differ substantially from those in the ground *** is suggested that in systems with competing instabilities,each polar phase has its optimal octahedral rotation pattern which stabilizes this phase and creates a potential barrier preventing this phase to be transformed into other structures.

关键词： Ferroelectricity competing instabilities strain effects metastable phases strontium titanate