The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
Michel Humbert - One of the best experts on this subject based on the ideXlab platform.
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determination of the habit plane characteristics in the β α phase transformation induced by stress in ti 5al 2sn 4zr 4mo 2cr 1fe
Acta Materialia, 2002Co-Authors: F. Zimmermann, Michel HumbertAbstract:Abstract The characteristics of the habit planes of the α″ orthorhombic Martensite Plates, induced by stress within a commercial sheet of Ti–5Al–2Sn–4Zr–4Mo–2Cr–1Fe have been investigated. First, the orientations of several grains in BCC phase which presented at least one α″ orthorhombic Martensite Plate, were determined by EBSD. The Miller indexes of habit planes within a parent grain were deduced from the intersection lines of the Martensite Plates on two perpendicular sides of the sample and from the orientation of the parent grain. These data are compared to the characteristics of the habit planes, calculated from the phenomenological theory of the martensitic transformation proposed by Wechsler, Liebermann and Read. The different results and their dispersions are analysed in this contribution.
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Determination of the habit plane characteristics in the β–α′ phase transformation induced by stress in Ti–5Al–2Sn–4Zr–4Mo–2Cr–1Fe
Acta Materialia, 2002Co-Authors: F. Zimmermann, Michel HumbertAbstract:Abstract The characteristics of the habit planes of the α″ orthorhombic Martensite Plates, induced by stress within a commercial sheet of Ti–5Al–2Sn–4Zr–4Mo–2Cr–1Fe have been investigated. First, the orientations of several grains in BCC phase which presented at least one α″ orthorhombic Martensite Plate, were determined by EBSD. The Miller indexes of habit planes within a parent grain were deduced from the intersection lines of the Martensite Plates on two perpendicular sides of the sample and from the orientation of the parent grain. These data are compared to the characteristics of the habit planes, calculated from the phenomenological theory of the martensitic transformation proposed by Wechsler, Liebermann and Read. The different results and their dispersions are analysed in this contribution.
F. Zimmermann - One of the best experts on this subject based on the ideXlab platform.
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determination of the habit plane characteristics in the β α phase transformation induced by stress in ti 5al 2sn 4zr 4mo 2cr 1fe
Acta Materialia, 2002Co-Authors: F. Zimmermann, Michel HumbertAbstract:Abstract The characteristics of the habit planes of the α″ orthorhombic Martensite Plates, induced by stress within a commercial sheet of Ti–5Al–2Sn–4Zr–4Mo–2Cr–1Fe have been investigated. First, the orientations of several grains in BCC phase which presented at least one α″ orthorhombic Martensite Plate, were determined by EBSD. The Miller indexes of habit planes within a parent grain were deduced from the intersection lines of the Martensite Plates on two perpendicular sides of the sample and from the orientation of the parent grain. These data are compared to the characteristics of the habit planes, calculated from the phenomenological theory of the martensitic transformation proposed by Wechsler, Liebermann and Read. The different results and their dispersions are analysed in this contribution.
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Determination of the habit plane characteristics in the β–α′ phase transformation induced by stress in Ti–5Al–2Sn–4Zr–4Mo–2Cr–1Fe
Acta Materialia, 2002Co-Authors: F. Zimmermann, Michel HumbertAbstract:Abstract The characteristics of the habit planes of the α″ orthorhombic Martensite Plates, induced by stress within a commercial sheet of Ti–5Al–2Sn–4Zr–4Mo–2Cr–1Fe have been investigated. First, the orientations of several grains in BCC phase which presented at least one α″ orthorhombic Martensite Plate, were determined by EBSD. The Miller indexes of habit planes within a parent grain were deduced from the intersection lines of the Martensite Plates on two perpendicular sides of the sample and from the orientation of the parent grain. These data are compared to the characteristics of the habit planes, calculated from the phenomenological theory of the martensitic transformation proposed by Wechsler, Liebermann and Read. The different results and their dispersions are analysed in this contribution.
Peter M. Anderson - One of the best experts on this subject based on the ideXlab platform.
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Mechanisms for phase transformation induced slip in shape memory alloy micro-crystals
Acta Materialia, 2017Co-Authors: Harshad M. Paranjape, M.l. Bowers, Michael J. Mills, Peter M. AndersonAbstract:Abstract Compression of a single crystal, superelastic NiTi shape memory alloy (SMA) micro-pillar and the stress-field around an ellipsoidal twinned Martensite (M) Plate embedded in an austenite (A) matrix were simulated using a coupled phase transformation and crystal plasticity model. Post-mortem transmission electron microscopy (TEM) analysis of the dislocation structures in a foil extracted from a compressed NiTi micro-pillar was also performed. Based on these modeling and experimental data, we propose mechanisms for phase-transformation-induced defect generation in superelastically stressed NiTi SMA. The geometry of the simulated slip bands shows that dislocations nucleate and grow in the austenite phase adjacent to a growing or receding Martensite Plate to accommodate local strain gradients. The simulated resolved shear stress on individual slip systems, and Burgers vector analysis of dislocations in the TEM data show that the slip system and amount of slip activity depend on the magnitude of the strain gradients, which are controlled by the Martensite crystallography, the dynamics of Martensite Plate growth, and scale of the twinned structure and A-M interface. In addition to a[0 1 0] (1 0 1 ¯ ) and a [0 0 1] ( 1 ¯ 1 0) slip systems observed in prior experiments, we report the activation of a third slip system: a[0 0 1](1 1 0). We show that the three slip systems are likely to be active at different locations around a Martensite Plate. The modeling component in this work complements ex-situ TEM characterization by furnishing the resolved shear stress and slip activity on austenite slip systems throughout the cyclic loading.
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Characterization and modeling of defects generated in pseudoelastically deformed NiTi microcrystals
Scripta Materialia, 2014Co-Authors: M.l. Bowers, Xiang Chen, M. De Graef, Peter M. Anderson, Michael J. MillsAbstract:[1 1 0]-Oriented micropillars of 50.7 at.% NiTi were compressed to stress-induce a single Martensite Plate. Scanning transmission electron microscopy identified two distinct slip systems in the prior transformation zone with dislocation loops of alternating Burgers vectors and a doubly periodic dislocation substructure. Micromechanics-based modeling predicts these systems to be dominant for a specific Martensite Plate type and correlates these observations with the alternating stress state near twinned Martensite Plates. This combined experiment–modeling approach provides new mechanistic insight into defect generation during pseudoelastic cycling.
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transformation induced plasticity during pseudoelastic deformation in ni ti microcrystals
Acta Materialia, 2009Co-Authors: D M Norfleet, Peter M. Anderson, Peter Maxwell Sarosi, Sivom Manchiraju, Martin F X Wagner, Michael D Uchic, M J MillsAbstract:Abstract [1 1 0]-oriented microcrystals of solutionized 50.7 at.% Ni–Ti were prepared by focused ion beam machining and then tested in compression to investigate the stress-induced B2-to-B19′ transformation in the pseudoelastic regime. The compression results indicate a sharp onset of the transformation, consistent with little prior plasticity. Post-mortem scanning transmission electron microscopy reveals no apparent retained Martensite but rather a macroscopic band of dislocation activity within which are planar arrays of ∼100 nm dislocation loops involving a single a 〈0 1 0〉{1 0 1} slip system. Micromechanics analyses show that the angle of the band is consistent with activation of a favored Martensite Plate. Further, the stress from the individual variants within the Plate is shown to favor activation of the observed slip system. The work done by the applied stress during the B2-to-B19′ transformation is estimated to be ∼34 MJ m −3 at ambient temperature.
M J Mills - One of the best experts on this subject based on the ideXlab platform.
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transformation induced plasticity during pseudoelastic deformation in ni ti microcrystals
Acta Materialia, 2009Co-Authors: D M Norfleet, Peter M. Anderson, Peter Maxwell Sarosi, Sivom Manchiraju, Martin F X Wagner, Michael D Uchic, M J MillsAbstract:Abstract [1 1 0]-oriented microcrystals of solutionized 50.7 at.% Ni–Ti were prepared by focused ion beam machining and then tested in compression to investigate the stress-induced B2-to-B19′ transformation in the pseudoelastic regime. The compression results indicate a sharp onset of the transformation, consistent with little prior plasticity. Post-mortem scanning transmission electron microscopy reveals no apparent retained Martensite but rather a macroscopic band of dislocation activity within which are planar arrays of ∼100 nm dislocation loops involving a single a 〈0 1 0〉{1 0 1} slip system. Micromechanics analyses show that the angle of the band is consistent with activation of a favored Martensite Plate. Further, the stress from the individual variants within the Plate is shown to favor activation of the observed slip system. The work done by the applied stress during the B2-to-B19′ transformation is estimated to be ∼34 MJ m −3 at ambient temperature.
Philip J. Withers - One of the best experts on this subject based on the ideXlab platform.
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Micromechanics of stress-induced martensitic transformation
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2004Co-Authors: T. Mori, E.c. Oliver, Mark R. Daymond, Philip J. WithersAbstract:Abstract This work proposes that the structure of a twinned Martensite Plate is dependent upon temperature and stress. The uniaxial tensile stress required to induce the formation of a Martensite Plate is predicted to be smaller than that calculated under the assumption that the Plate has a fixed structure subject to the criterion of invariant plane strain (IPS). Using a mean field method, the analysis is extended to non-dilute Martensite volume fraction in order to obtain a stress–strain curve for the deformation of a single crystal. The curve shows a decrease in stress as transformation progresses. The implication of this result is discussed.