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Jicheng Zhao - One of the best experts on this subject based on the ideXlab platform.

  • effective evaluation of interfacial energy by matching precipitate sizes measured along a composition gradient with kampmann wagner numerical kwn modeling
    Scripta Materialia, 2019
    Co-Authors: Qiaofu Zhang, Surendra Kumar Makineni, J E Allison, Jicheng Zhao
    Abstract:

    Abstract A dual-anneal Diffusion Multiple was utilized to generate a composition gradient via a first anneal at a high temperature followed by a second anneal at a lower temperature to induce phase precipitation as a function of composition/supersaturation. By adjusting the interfacial energy value in simulations using the classical nucleation and growth theories as implemented in the Kampmann-Wagner numerical (KWN) model and matching the simulated average precipitate sizes at different compositions with the experimental measurements along the composition gradient, the Ni3Al/fcc interfacial energy in the Ni-Al system at 700 °C was effectively determined to be ~12 mJ/m2.

  • erratum to determination of the fe cr mo phase diagram at intermediate temperatures using dual anneal Diffusion Multiples
    Journal of Phase Equilibria and Diffusion, 2016
    Co-Authors: Siwei Cao, Jicheng Zhao
    Abstract:

    A recently developed dual-anneal Diffusion-Multiple approach is employed to the determination of the Fe-Cr-Mo phase diagram at intermediate temperatures. Diffusion Multiples of Fe-Cr-Ni-Co-Mo were first annealed at 1200 °C for 500 h to create wide ranges of solid solution compositions. Subsequent annealing of the Diffusion Multiples at individual intermediate temperatures induced various precipitate phases. Electron probe microanalysis (EPMA) across the interface between large precipitates and the matrix phase provided local equilibrium information for the establishment of equilibrium tie-lines which are utilized to construct the Fe-rich part of the Fe-Cr-Mo isothermal sections at 900 and 800 °C. The Mo-rich part of the isothermal sections at intermediate temperatures was not obtained due to the sluggish kinetics of precipitation and growth, resulting in too small precipitates for reliable EPMA composition evaluation. A complete 1200 °C isothermal section of the Fe-Cr-Mo system is also established from EPMA data on a water quenched Diffusion Multiple that was annealed at 1200 °C for 500 h only without a second anneal.

  • application of dual anneal Diffusion Multiples to the effective study of phase diagrams and phase transformations in the fe cr ni system
    Acta Materialia, 2015
    Co-Authors: Siwei Cao, Jicheng Zhao
    Abstract:

    Abstract A dual-anneal Diffusion Multiple (DADM) approach is developed for effective determination of intermediate-temperature phase diagrams that are critical to the establishment of reliable thermodynamic databases. A large amount of phase equilibrium data was obtained from DADMs to construct the Fe–Cr–Ni isothermal sections at 1200, 900, 800 and 700 °C. The DADM approach is also a systematic and effective way to study phase precipitation from wide ranges of compositions, thus generating rich atlases of microstructures induced by various transformations. The results from this study indicate that the body-centered cubic to sigma phase transformation in the Fe–Cr–Ni system took place initially through a massive transformation mechanism.

  • high efficiency combinatorial approach as an effective tool for accelerating metallic biomaterials research and discovery
    Materials Science and Engineering: C, 2014
    Co-Authors: X D Zhang, Jicheng Zhao, L B Liu, Jianxiu Wang, F Zheng, Z P Jin
    Abstract:

    Abstract A high-efficiency combinatorial approach has been applied to rapidly build the database of composition-dependent elastic modulus and hardness of the Ti–Ta and Ti–Zr–Ta systems. A Diffusion Multiple of the Ti–Zr–Ta system was manufactured, then annealed at 1173 K for 1800 h, and water quenched to room temperature. Extensive interDiffusion among Ti, Zr and Ta has taken place. Combining nanoindentation and electron probe micro-analysis (EPMA), the elastic modulus, hardness as well as composition across the Diffusion Multiple were determined. The composition/elastic modulus/hardness relationship of the Ti–Ta and Ti–Zr–Ta alloys has been obtained. It was found that the elastic modulus and hardness depend strongly on the Ta and Zr content. The result can be used to accelerate the discovery/development of bio-titanium alloys for different components in implant prosthesis.

  • thermal conductivity mapping of the ni al system and the beta nial phase in the ni al cr system
    Scripta Materialia, 2012
    Co-Authors: Jicheng Zhao, Xuan Zheng, David G Cahill
    Abstract:

    We use two examples to highlight the power of micron-scale-resolution thermal conductivity mapping on graded compositions created in a Diffusion-Multiple sample in rapid establishment of composition–phase–property relationships. The Ni–NiAl Diffusion couple example clearly shows the effects of solid solutioning, order–disorder transition, and compositional point defects on thermal conductivity. Thermal conductivity mapping of the beta-NiAl phase region of an Ni–Cr–NiAl Diffusion triple clearly shows that Cr substitutes for both Ni and Al sites in beta-NiAl without a strong preference, which is also found not to be strongly composition dependent.

Stefan Zaefferer - One of the best experts on this subject based on the ideXlab platform.

  • phase diagram mapping of the fe3al cr mo c pseudo quaternary system at 800 c using a new Diffusion Multiple technique
    Journal of Phase Equilibria and Diffusion, 2008
    Co-Authors: Satoru Kobayashi, Stefan Zaefferer
    Abstract:

    A new Diffusion-Multiple technique was used for mapping the phase diagram in the pseudo-quaternary Fe3Al-Cr-Mo-C system at 800 °C. The following five carbide phases were formed in an Fe3Al matrix phase (B2) with composition gradients of Cr, Mo, and C in the Diffusion-Multiple samples: κ-Fe3AlC, M5C, M6C, Cr7C3, and M2C (M: Mo, Cr, Al, and Fe). It was assumed that B2 phase is in equilibrium with κ, M5C, M6C, and Cr7C3 but not with M2C phase at 800 °C. Complex phase equilibria among those phases were efficiently mapped by the Diffusion-Multiple technique. The results from the technique were consistent with those obtained from the conventional bulk alloy method.

  • determination of phase equilibria in the fe3al cr mo c semi quaternary system using a new Diffusion Multiple technique
    Journal of Alloys and Compounds, 2008
    Co-Authors: Satoru Kobayashi, Stefan Zaefferer
    Abstract:

    A new Diffusion-Multiple (DM) technique was proposed to allow us mapping of quaternary phase diagrams. This technique utilizes a combination of DM technique to introduce two-dimensional composition gradients in a matrix phase and a conventional annealing heat treatment to have precipitation reactions in the matrix. Phase equilibria at 800 °C in the semi-quaternary Fe 3 Al-Cr-Mo-C system were determined with an assist from this technique. The following five carbide phases were precipitated in the Fe 3 Al matrix phase (B2) with composition gradients ofCr, Mo and C: K-Fe 3 AlC, M 6 C H , M 6 C L , Cr 7 C 3 and M 2 C (M: Mo, Cr and Fe, the two M 6 C phases are distinguished by their C and Cr contents.). It was found from our DM technique that the four-phase equilibrium of M 6 C H + M 6 C L + Cr 7 C 3 +B2 exists. Microstructure analysis of several bulk alloys as well as DM samples revealed that the three-phase equilibrium of M 6 C L + K + B2 in the Fe 3 Al-Mo-C system changes to that of M 6 C L + Cr 7 C 3 + B2 with increasing Cr content through the following three four-phase equilibria: (1) M 6 C H + M 6 C L + K + B2, (2) M 6 C u + Cr 7 C 3 + K + B2, (3) M 6 C H + M 6 C L + Cr 7 C 3 + B2. The M 2 C phase is thought to be not in equilibrium with the Fe 3 Al matrix phase at 800 °C.

Siwei Cao - One of the best experts on this subject based on the ideXlab platform.

  • erratum to determination of the fe cr mo phase diagram at intermediate temperatures using dual anneal Diffusion Multiples
    Journal of Phase Equilibria and Diffusion, 2016
    Co-Authors: Siwei Cao, Jicheng Zhao
    Abstract:

    A recently developed dual-anneal Diffusion-Multiple approach is employed to the determination of the Fe-Cr-Mo phase diagram at intermediate temperatures. Diffusion Multiples of Fe-Cr-Ni-Co-Mo were first annealed at 1200 °C for 500 h to create wide ranges of solid solution compositions. Subsequent annealing of the Diffusion Multiples at individual intermediate temperatures induced various precipitate phases. Electron probe microanalysis (EPMA) across the interface between large precipitates and the matrix phase provided local equilibrium information for the establishment of equilibrium tie-lines which are utilized to construct the Fe-rich part of the Fe-Cr-Mo isothermal sections at 900 and 800 °C. The Mo-rich part of the isothermal sections at intermediate temperatures was not obtained due to the sluggish kinetics of precipitation and growth, resulting in too small precipitates for reliable EPMA composition evaluation. A complete 1200 °C isothermal section of the Fe-Cr-Mo system is also established from EPMA data on a water quenched Diffusion Multiple that was annealed at 1200 °C for 500 h only without a second anneal.

  • application of dual anneal Diffusion Multiples to the effective study of phase diagrams and phase transformations in the fe cr ni system
    Acta Materialia, 2015
    Co-Authors: Siwei Cao, Jicheng Zhao
    Abstract:

    Abstract A dual-anneal Diffusion Multiple (DADM) approach is developed for effective determination of intermediate-temperature phase diagrams that are critical to the establishment of reliable thermodynamic databases. A large amount of phase equilibrium data was obtained from DADMs to construct the Fe–Cr–Ni isothermal sections at 1200, 900, 800 and 700 °C. The DADM approach is also a systematic and effective way to study phase precipitation from wide ranges of compositions, thus generating rich atlases of microstructures induced by various transformations. The results from this study indicate that the body-centered cubic to sigma phase transformation in the Fe–Cr–Ni system took place initially through a massive transformation mechanism.

David G Cahill - One of the best experts on this subject based on the ideXlab platform.

  • thermal conductivity mapping of the ni al system and the beta nial phase in the ni al cr system
    Scripta Materialia, 2012
    Co-Authors: Jicheng Zhao, Xuan Zheng, David G Cahill
    Abstract:

    We use two examples to highlight the power of micron-scale-resolution thermal conductivity mapping on graded compositions created in a Diffusion-Multiple sample in rapid establishment of composition–phase–property relationships. The Ni–NiAl Diffusion couple example clearly shows the effects of solid solutioning, order–disorder transition, and compositional point defects on thermal conductivity. Thermal conductivity mapping of the beta-NiAl phase region of an Ni–Cr–NiAl Diffusion triple clearly shows that Cr substitutes for both Ni and Al sites in beta-NiAl without a strong preference, which is also found not to be strongly composition dependent.

  • thermal conductivity imaging at micrometre scale resolution for combinatorial studies of materials
    Nature Materials, 2004
    Co-Authors: Scott T Huxtable, David G Cahill, Vincent Fauconnier, Jeffrey O White, Jicheng Zhao
    Abstract:

    Combinatorial methods offer an efficient approach for the development of new materials. Methods for generating combinatorial samples of materials, and methods for characterizing local composition and structure by electron microprobe analysis and electron-backscatter diffraction are relatively well developed. But a key component for combinatorial studies of materials is high-spatial-resolution measurements of the property of interest, for example, the magnetic, optical, electrical, mechanical or thermal properties of each phase, composition or processing condition. Advances in the experimental methods used for mapping these properties will have a significant impact on materials science and engineering. Here we show how time-domain thermoreflectance can be used to image the thermal conductivity of the cross-section of a Nb-Ti-Cr-Si Diffusion Multiple, and thereby demonstrate rapid and quantitative measurements of thermal transport properties for combinatorial studies of materials. The lateral spatial resolution of the technique is 3.4 microm, and the time required to measure a 100 x 100 pixel image is approximately 1 h. The thermal conductivity of TiCr(2) decreases by a factor of two in crossing from the near-stoichiometric side of the phase to the Ti-rich side; and the conductivity of (Ti,Nb)(3)Si shows a strong dependence on crystalline orientation.

Satoru Kobayashi - One of the best experts on this subject based on the ideXlab platform.

  • phase diagram mapping of the fe3al cr mo c pseudo quaternary system at 800 c using a new Diffusion Multiple technique
    Journal of Phase Equilibria and Diffusion, 2008
    Co-Authors: Satoru Kobayashi, Stefan Zaefferer
    Abstract:

    A new Diffusion-Multiple technique was used for mapping the phase diagram in the pseudo-quaternary Fe3Al-Cr-Mo-C system at 800 °C. The following five carbide phases were formed in an Fe3Al matrix phase (B2) with composition gradients of Cr, Mo, and C in the Diffusion-Multiple samples: κ-Fe3AlC, M5C, M6C, Cr7C3, and M2C (M: Mo, Cr, Al, and Fe). It was assumed that B2 phase is in equilibrium with κ, M5C, M6C, and Cr7C3 but not with M2C phase at 800 °C. Complex phase equilibria among those phases were efficiently mapped by the Diffusion-Multiple technique. The results from the technique were consistent with those obtained from the conventional bulk alloy method.

  • determination of phase equilibria in the fe3al cr mo c semi quaternary system using a new Diffusion Multiple technique
    Journal of Alloys and Compounds, 2008
    Co-Authors: Satoru Kobayashi, Stefan Zaefferer
    Abstract:

    A new Diffusion-Multiple (DM) technique was proposed to allow us mapping of quaternary phase diagrams. This technique utilizes a combination of DM technique to introduce two-dimensional composition gradients in a matrix phase and a conventional annealing heat treatment to have precipitation reactions in the matrix. Phase equilibria at 800 °C in the semi-quaternary Fe 3 Al-Cr-Mo-C system were determined with an assist from this technique. The following five carbide phases were precipitated in the Fe 3 Al matrix phase (B2) with composition gradients ofCr, Mo and C: K-Fe 3 AlC, M 6 C H , M 6 C L , Cr 7 C 3 and M 2 C (M: Mo, Cr and Fe, the two M 6 C phases are distinguished by their C and Cr contents.). It was found from our DM technique that the four-phase equilibrium of M 6 C H + M 6 C L + Cr 7 C 3 +B2 exists. Microstructure analysis of several bulk alloys as well as DM samples revealed that the three-phase equilibrium of M 6 C L + K + B2 in the Fe 3 Al-Mo-C system changes to that of M 6 C L + Cr 7 C 3 + B2 with increasing Cr content through the following three four-phase equilibria: (1) M 6 C H + M 6 C L + K + B2, (2) M 6 C u + Cr 7 C 3 + K + B2, (3) M 6 C H + M 6 C L + Cr 7 C 3 + B2. The M 2 C phase is thought to be not in equilibrium with the Fe 3 Al matrix phase at 800 °C.