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Eric Hug - One of the best experts on this subject based on the ideXlab platform.
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Secondary Creep stage behavior of copper clad aluminum thin wires submitted to a moderate temperature level
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2018Co-Authors: Antoine Gueydan, Eric HugAbstract:Abstract This work focuses on the role of the microstructure on the Creep behavior of thin copper-clad aluminum (CCA) wires. Creep tests were performed at 150 °C on hard drawn and annealed CCA and on pure metals. It is shown that the Cu-Al interface of CCA ensures a mechanical resistance leading to lower Creep velocities than for metals. Creep mechanisms are driven by aluminum at lower stresses and copper for higher stresses, independently of the physical nature of the interface.
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Secondary Creep stage behavior of copper-clad aluminum thin wires submitted to a moderate temperature level
Materials Science and Engineering: A, 2018Co-Authors: Antoine Gueydan, Eric HugAbstract:This work focuses on the role of the microstructure on the Creep behavior of thin copper-clad aluminum (CCA) wires. Creep tests were performed at 150 degrees C on hard drawn and annealed CCA and on pure metals. It is shown that the Cu-Al interface of CCA ensures a mechanical resistance leading to lower Creep velocities than for metals. Creep mechanisms are driven by aluminum at lower stresses and copper for higher stresses, independently of the physical nature of the interface.
Antoine Gueydan - One of the best experts on this subject based on the ideXlab platform.
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Secondary Creep stage behavior of copper clad aluminum thin wires submitted to a moderate temperature level
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2018Co-Authors: Antoine Gueydan, Eric HugAbstract:Abstract This work focuses on the role of the microstructure on the Creep behavior of thin copper-clad aluminum (CCA) wires. Creep tests were performed at 150 °C on hard drawn and annealed CCA and on pure metals. It is shown that the Cu-Al interface of CCA ensures a mechanical resistance leading to lower Creep velocities than for metals. Creep mechanisms are driven by aluminum at lower stresses and copper for higher stresses, independently of the physical nature of the interface.
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Secondary Creep stage behavior of copper-clad aluminum thin wires submitted to a moderate temperature level
Materials Science and Engineering: A, 2018Co-Authors: Antoine Gueydan, Eric HugAbstract:This work focuses on the role of the microstructure on the Creep behavior of thin copper-clad aluminum (CCA) wires. Creep tests were performed at 150 degrees C on hard drawn and annealed CCA and on pure metals. It is shown that the Cu-Al interface of CCA ensures a mechanical resistance leading to lower Creep velocities than for metals. Creep mechanisms are driven by aluminum at lower stresses and copper for higher stresses, independently of the physical nature of the interface.
Uwe Glatzel - One of the best experts on this subject based on the ideXlab platform.
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influence of oxidation on near surface γ fraction and resulting Creep behaviour of single crystal ni base superalloy m247lc sx
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2013Co-Authors: Matthias Bensch, Christian Konrad, Ernst Fleischmann, Uwe GlatzelAbstract:Abstract Literature results show that Creep properties differ significantly with specimen thickness. This behaviour can be attributed to the influence of oxidation. In the present work the effect of oxidation on Creep of single crystal nickel-based superalloy M247LC SX samples with varying thickness was studied. Results reveal that aluminium depletion during oxidation results in a modified matrix/γ′-microstructure in the near-surface regions. The differences from nominal alloy composition were measured as a function of distance from the oxidised surface. From these measurements five compositions were chosen representing different positions within the oxidised specimen. All of these alloys were cast as single crystals with different γ′ fractions. Creep experiments were carried out at 980 °C in vacuum to determine the influence of the varying γ′ fraction on Secondary Creep. The dependence of stress level on Creep rate was approximated by a Norton Creep law. The stress exponent n plotted against the γ′ fraction shows a S-shaped behaviour almost doubling at 50% volume fraction. This behaviour suggests a change in the dominant Creep mechanism. Using precipitate hardening theories this progression can be attributed to the transition of dislocation movement from cutting ordered γ′ precipitates to Orowan bowing mechanism with decreasing γ′ fraction. These results enable a correlation of oxidation-affected γ′ fraction and Secondary Creep, which is essential for the design and the improved prediction of Creep deformation of thin sections of single crystal turbine blades.
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modelling and analysis of the oxidation influence on Creep behaviour of thin walled structures of the single crystal nickel base superalloy rene n5 at 980 c
Acta Materialia, 2010Co-Authors: Matthias Bensch, Johannes Preusner, Rainer Huttner, Georgia Obigodi, Sannakaisa Virtanen, Johannes Gabel, Uwe GlatzelAbstract:Abstract Creep test results of thin-walled specimens of the single-crystal nickel-base superalloy Rene N5 at 980 °C under vacuum as well as under air show different Creep properties depending on material thickness and atmosphere. The differences in Creep strength and strain were analysed based on a Creep-oxidation model. The model specifies the primary and Secondary Creep stages of thin-walled specimens by a sequence of layers. The model takes different zones affected by oxidation into account. Four layers were experimentally observed and considered in the model: oxide layer, γ ′-free layer, γ ′-reduced layer and the two-phase substrate in the sample as centre. Material parameters for growth laws of each layer were identified both by experimental analyses and by thermodynamic simulations. The final Creep-oxidation model characterizes the Creep behaviour of samples with small thicknesses and low initial stress with high accuracy.
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a dislocation density based material model to simulate the anisotropic Creep behavior of single phase and two phase single crystals
International Journal of Plasticity, 2009Co-Authors: Johannes Preusner, Yegor Rudnik, Holger Brehm, Rainer Volkl, Uwe GlatzelAbstract:Abstract The primary and Secondary Creep behavior of single crystals is observed by a material model using evolution equations for dislocation densities on individual slip systems. An interaction matrix defines the mutual influence of dislocation densities on different glide systems. Face-centered cubic (fcc), body-centered cubic (bcc) and hexagonal closed packed (hcp) lattice structures have been investigated. The material model is implemented in a finite element method to analyze the orientation dependent Creep behavior of two-phase single crystals. Three finite element models are introduced to simulate Creep of a γ′ strengthened nickel base superalloy in 〈1 0 0〉, 〈1 1 0〉 and 〈1 1 1〉 directions. This approach allows to examine the influence of crystal slip and cuboidal microstructure on the deformation process.
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anisotropic Creep properties of the nickel base superalloy cmsx 4
Acta Materialia, 1996Co-Authors: Volker Sass, Uwe Glatzel, Monika FellerkniepmeierAbstract:Single crystals of the superalloy CMSX-4 were tested in tensile Creep in order to investigate the influence of orientation on the Creep behaviour at temperatures of 1123 and 1253 K. The Creep response of the CMSX-4 crystals was found to be highly anisotropic at the lower temperature of 1123 K. In particular, the primary Creep behaviour of near [001] and [011] oriented crystals is highly sensitive to even small misorientations. Secondary Creep strength deteriorates considerably in the order [001]-[011]-[111]. At 1253 K the Creep anisotropy is clearly reduced, the Creep strength of the [111] orientation, however, remains poor. The evolution of the microstructure during Creep was studied as a function of strain and orientation and the relationship between deformation mechanisms and Creep properties is discussed.
C J Boehlert - One of the best experts on this subject based on the ideXlab platform.
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the effect of molybdenum on the microstructure and Creep behavior of ti 24al 17nb xmo alloys and ti 24al 17nb xmo sic fiber composites
Journal of Materials Science, 2008Co-Authors: J P Quast, C J BoehlertAbstract:The effect of molybdenum (Mo) on the microstructure and Creep behavior of nominally Ti–24Al–17Nb (at.%) alloys and their continuously reinforced SiC-fiber composites (fiber volume fraction = 0.35) was investigated. Constant-load, tensile-Creep experiments were performed in the stress range of 10–275 MPa at 650 °C in air. A Ti–24Al–17Nb–2.3Mo (at.%) alloy exhibited significantly greater Creep resistance than a Ti–24Al–17Nb–0.66Mo (at.%) alloy, and correspondingly a 90°-oriented Ultra SCS-6/Ti–24Al–17Nb–2.3Mo metal matrix composite (MMC) exhibited significantly greater Creep resistance than an Ultra SCS-6/Ti–24Al–17Nb–0.66Mo MMC. Thus, the addition of 2.3 at.% Mo significantly improved the Creep resistance of both the alloy and the MMC. An Ultra SCS-6 Ti–25Al–17Nb–1.1Mo (at.%) MMC exhibited Creep resistance similar to that of the Ultra SCS-6/Ti–25Al–17Nb–2.3Mo (at.%). Using a modified Crossman model, the MMC Secondary Creep rates were predicted from the monolithic matrix alloys’ Secondary Creep rates. For identical Creep temperatures and applied stresses, the 90°-oriented MMCs exhibited greater Creep rates than their monolithic matrix alloy counterparts. This was explained to be a result of the low interfacial bond strength between the matrix and the fiber, measured using a cruciform test methodology, and was in agreement with the modified Crossman model. Scanning electron microscopy observations indicated that debonding occurred within the carbon layers of the fiber-matrix interface.
Miguel Justino Ribeiro Barboza - One of the best experts on this subject based on the ideXlab platform.
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nitride coatings improve ti 6al 4v alloy behavior in Creep tests
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2016Co-Authors: Veronica Mara Cortez Alves De Oliveira, A M Vazquez, C Aguiar, A Robin, Miguel Justino Ribeiro BarbozaAbstract:Abstract This study aimed to evaluate the effect of plasma-assisted PVD TiN and TiAlN/TiAlCrN coatings on the Ti-6Al-4V alloy under Creep conditions at 600 °C. Microstructural and surface coating analysis were investigated using XRD, optical and scanning microscopy and isothermal oxidation. The results showed that the TiN coated sample showed the lowest Secondary Creep rate values for stresses greater than 222 MPa. Below 222 MPa, the TiAlN/TiAlCrN coated sample presented a Secondary Creep rate value higher than the TiN coated sample. This behavior was due to TiAlN/TiAlCrN oxidation resistance that, according to isothermal oxidation tests, did not suffer oxidation at 600 °C. The stress exponent analysis indicated that the main Creep mechanism was controlled by climbing dislocations. The fracture mode is similar for all conditions studied and displayed transgranular fracture with decohesion of intergranular regions. Finally, the coated samples contribute to improved oxidation resistance, reduced damage tolerance parameter (λ) and increased lifetime of Ti-6Al-4V alloy.