“3D reconstruction of a Ni51Ti49 alloy with precipitates by FIB-SEM alice-and-view”. Cao S, Tirry W, Schryvers D, Materia Japan 46, 803 (2007)
Keywords: A3 Journal article; Electron microscopy for materials research (EMAT)
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“3D reconstruction of Ni4Ti3 precipitates in a Ni51Ti49 alloy in a FIB/SEM dual-beam system”. Cao S, Tirry W, van den Broek W, Schryvers D, Materials science forum 583, 277 (2008). http://doi.org/10.4028/www.scientific.net/MSF.583.277
Abstract: Ni4Ti3 precipitates play an important role in the shape memory and superelastic behaviour of thermo-mechanically treated Ni-Ti material. The 3D morphology and distribution of such precipitates with lenticular shape and rhombohedral atomic structure in the austenitic B2 matrix of a binary Ni-rich Ni-Ti alloy has been elucidated via a slice view procedure in a Dual-Beam FIB/SEM system. With the sequence of cross-section SE images obtained from the SEM, a 3D reconstruction has been achieved after proper alignment and image processing, from which both qualitative and quantitative analysis can be performed. Careful imaging is needed to ensure that all variants of the precipitates are observed with equal probability, regardless sample orientation. Moreover, due to the weak contrast of the precipitates, proper imaging conditions need to be selected to allow for semi-automated image treatment. Finally, a volume ratio of 10.2% for the Ni4Ti3 precipitates could be calculated, summed over all variants, which yields a net composition of Ni50.36Ti49.64 for the matrix, leading to an increase of 113 degrees for the martensitic start temperature Ms. Also, the expected relative orientation of the different variants of the precipitates could be confirmed. In the near future, other quantitative measures on the distribution of the precipitates can be expected.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
DOI: 10.4028/www.scientific.net/MSF.583.277
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“3D strain fields surrounding Ni4Ti3: direct measurement and correlation with the R-phase”. Tirry W, Schryvers D, , 02032 (2009). http://doi.org/10.1051/esomat/200902032
Abstract: Strain fields introduced by coherent Ni4Ti3 precipitates in austenitic Ni-Ti are believed to be a possible origin of why the R-phase transformation is introduced as an extra step before transforming to the B19'. The presence of this strain field was already confirmed in the past by conventional transmission electron microscopy (TEM) techniques and measured quantitatively by high resolution TEM (HRTEM). This time the geometrical phase method is applied on HRTEM micrographs to measure the full 3D strain tensor of the strain fields. Since each atomic resolution micrograph only results in a 2D measurement of the strain, observations in two different zone orientations are combined to retrieve the 3 x 3 strain tensor. In this work observations in a [1-1 1](B2) and [1 0-1](B2) zone orientation are used and this in case of precipitates with a diameter of around 50nm. In a next step the measured strain tensor is compared to the calculated eigenstrain of the R-phase in reference to the B2 matrix. This comparison shows that the introduced strain is very similar to the eigenstrain of one R-phase variant. Since for both structures, Ni4Ti3 and R-phase, four orientation variants are possible, each variant of the R-phase is thus able to accommodate the strain field of one of the Ni4Ti3 variants.
Keywords: P1 Proceeding; Electron microscopy for materials research (EMAT)
DOI: 10.1051/esomat/200902032
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“Advanced TEM and SEM methods applied to 3D nano- and microstructural investigations of Ni4Ti3 precipitates in Ni-Ti (SMA)”. Schryvers D, Tirry W, Cao S, Diffusion and defect data : solid state data : part B : solid state phenomena 172/174, 229 (2011). http://doi.org/10.4028/www.scientific.net/SSP.172-174.229
Abstract: Two different kinds of experimental approaches yielding three-dimensional structural information on metastable semi-coherent precipitates are demonstrated. By combining high-resolution images from two independent viewing directions a full description of the strain field surrounding a nano-sized Ni4Ti3 precipitate in Ni-Ti can be obtained. The principal axes and strains correlate well with the transformation strain of the observed R-phase transformation close to the precipitate. Using a slice-and-view procedure in a FIB/SEM dual-beam instrument, a three-dimensional voxel dataset is produced from which morphological and distributional information on the same precipitates can be obtained yielding new insight into the particular transformation paths of these alloys, relevant for their functional behaviour.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
DOI: 10.4028/www.scientific.net/SSP.172-174.229
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“Advanced TEM investigations on Ni-Ti shape memory material: strain and concentration gradients surrounding Ni4Ti3 precipitates”. Schryvers D, Tirry W, Yang Z, , 329 (2005)
Abstract: Lattice deformations and concentration gradients surrounding Ni4Ti3 precipitates grown by appropriate annealing in a Ni51Ti49 B2 austenite matrix are determined by a combination of TEM techniques. Quantitative Fourier analysis of HRTEM images reveals a deformed nanoscale region with lattice deformations up to 2% while EELS and EDX indicate a Ni depleted zone up to 150 nm away from the matrix-precipitate interface.
Keywords: P1 Proceeding; Electron microscopy for materials research (EMAT)
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“Advanced three-dimensional electron microscopy techniques in the quest for better structural and functional materials”. Schryvers D, Cao S, Tirry W, Idrissi H, Van Aert S, Science and technology of advanced materials 14, 014206 (2013). http://doi.org/10.1088/1468-6996/14/1/014206
Abstract: After a short review of electron tomography techniques for materials science, this overview will cover some recent results on different shape memory and nanostructured metallic systems obtained by various three-dimensional (3D) electron imaging techniques. In binary NiTi, the 3D morphology and distribution of Ni4Ti3 precipitates are investigated by using FIB/SEM slice-and-view yielding 3D data stacks. Different quantification techniques will be presented including the principal ellipsoid for a given precipitate, shape classification following a Zingg scheme, particle distribution function, distance transform and water penetration. The latter is a novel approach to quantifying the expected matrix transformation in between the precipitates. The different samples investigated include a single crystal annealed with and without compression yielding layered and autocatalytic precipitation, respectively, and a polycrystal revealing different densities and sizes of the precipitates resulting in a multistage transformation process. Electron tomography was used to understand the interaction between focused ion beam-induced Frank loops and long dislocation structures in nanobeams of Al exhibiting special mechanical behaviour measured by on-chip deposition. Atomic resolution electron tomography is demonstrated on Ag nanoparticles in an Al matrix.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.798
Times cited: 6
DOI: 10.1088/1468-6996/14/1/014206
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“Analytical TEM investigations on concentration gradients surrounding Ni4Ti3 precipitates in Ni-Ti shape memory material”. Yang Z, Tirry W, Schryvers D, Scripta materialia 52, 1129 (2005). http://doi.org/10.1016/j.scriptamat.2005.02.013
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.747
Times cited: 49
DOI: 10.1016/j.scriptamat.2005.02.013
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“Applications of advanced transmission electron microscopic techniques to Ni-Ti based shape memory materials”. Schryvers D, Potapov P, Santamarta R, Tirry W, Materials science and engineering: part A: structural materials: properties, microstructure and processing 378, 11 (2004). http://doi.org/10.1016/j.msea.2003.10.325
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.094
Times cited: 6
DOI: 10.1016/j.msea.2003.10.325
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“Cross-section transmission electron microscopy characterization of the near-surface structure of medical Nitinol superelastic tubing”. Potapov PL, Tirry W, Schryvers D, Sivel VGM, Wu M-Y, Aslanidis D, Zandbergen H, Journal of materials science: materials in medicine 18, 483 (2007). http://doi.org/10.1007/s10856-007-2008-y
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.325
Times cited: 14
DOI: 10.1007/s10856-007-2008-y
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“Dynamic shear localization in Ti6Al4V”. Peirs J, Verleysen P, Tirry W, Rabet L, Schryvers D, Degrieck J, Procedia Engineering
T2 –, 11th International Conference on the Mechanical Behavior of Materials, (ICM), 2011, Como, ITALY (ICM11) , 1 (2011). http://doi.org/10.1016/j.proeng.2011.04.386
Abstract: The alloy Ti6Al4V is known to be prone to the formation of adiabatic shear bands when dynamically loaded in shear. This causes a catastrophic decrease of the load carrying capacity and is usually followed by fracture. Although, the main mechanism is recognized to be the competition between strain hardening and thermal softening, a detailed understanding of the role of microstructural plasticity mechanisms and macroscopic loading conditions does not exist yet. To study strain localization and shear fracture, different high strain rate shear tests have been carried out: compression of hat-shaped specimens, torsion of thin walled tubular specimens and in-plane shear tests. The value of the three techniques in studying shear localization is evaluated. Post-mortem analysis of the fracture surface and the materials' microstructure is performed with optical and electron microscopy. In all cases a ductile fracture is observed. SEM and TEM techniques are used to study the local microstructure and composition in the shear band and as such the driving mechanism for the ASB formation. (C) 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of ICM11
Keywords: P1 Proceeding; Electron microscopy for materials research (EMAT)
Times cited: 4
DOI: 10.1016/j.proeng.2011.04.386
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“Electron-diffraction structure refinement of Ni4Ti3 precipitates in Ni52Ti48”. Tirry W, Schryvers D, Jorissen K, Lamoen D, Acta crystallographica: section B: structural science 62, 966 (2006). http://doi.org/10.1107/S0108768106036457
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 30
DOI: 10.1107/S0108768106036457
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“Electron energy-loss spectroscopy and first-principles calculation studies on a Ni-Ti shape memory alloy”. Yang Z, Tirry W, Lamoen D, Kulkova S, Schryvers D, Acta materialia 56, 395 (2008). http://doi.org/10.1016/j.actamat.2007.10.001
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 5.301
Times cited: 20
DOI: 10.1016/j.actamat.2007.10.001
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“Hardening in relation with microstructure evolution of high purity \alpha-titanium deformed under monotonic and cyclic simple shear loadings at room temperature”. Bouvier S, Benmhenni N, Tirry W, Gregory F, Nixon ME, Cazacu O, Rabet L, Materials science and engineering: part A: structural materials: properties, microstructure and processing 535, 12 (2012). http://doi.org/10.1016/j.msea.2011.12.033
Abstract: The aim of this paper is to gain understanding of the quasi-static, large strain deformation behavior at room-temperature of high-purity alpha-Ti with an initial split-basal texture. Simple shear tests were conducted along different directions in order to quantify the material's anisotropy and hardening evolution for different strain paths such as monotonic, Bauschinger, and cyclic loadings. The stress-strain curves indicate that the material displays strong anisotropy in the flow behavior. In order to capture the link between microstructure evolution (occurrence of twinning, grain size evolution, etc.) and the macroscopic response, a thoroughly detailed multi-scale characterization using scanning electron microscope (SEM) observations and electron backscattered diffraction (EBSD) analysis was also conducted. Specifically, EBSD analyses indicate that the twin activity and grain fragmentation are responsible for the observed difference between the macroscopic hardening rates corresponding to different directions and loading paths. (C) 2011 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 3.094
Times cited: 22
DOI: 10.1016/j.msea.2011.12.033
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“High-quality sample preparation by low kV FIB thinning for analytical TEM measurements”. Bals S, Tirry W, Geurts R, Yang Z, Schryvers D, Microscopy and microanalysis 13, 80 (2007). http://doi.org/10.1017/S1431927607070018
Abstract: Focused ion beam specimen preparation has been used for NiTi samples and SrTiO(3)/SrRuO(3) multilayers with prevention of surface amorphization and Ga implantation by a 2-kV cleaning procedure. Transmission electron microscopy techniques show that the samples are of high quality with a controlled thickness over large scales. Furthermore, preferential thinning effects in multicompounds are avoided, which is important when analytical transmission electron microscopy measurements need to be interpreted in a quantitative manner. The results are compared to similar measurements acquired for samples obtained using conventional preparation techniques such as electropolishing for alloys and ion milling for oxides.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.891
Times cited: 82
DOI: 10.1017/S1431927607070018
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“High resolution TEM study of Ni4Ti3 precipitates in austenitic Ni51Ti49”. Tirry W, Schryvers D, Materials science and engineering: part A: structural materials: properties, microstructure and processing 378, 157 (2004). http://doi.org/10.1016/j.msea.2003.10.336
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.094
Times cited: 19
DOI: 10.1016/j.msea.2003.10.336
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“Importance of twinning in static and dynamic compression of a Ti-6Al-4V titanium alloy with an equiaxed microstructure”. Coghe F, Tirry W, Rabet L, Schryvers D, Van Houtte P, Materials science and engineering: part A: structural materials: properties, microstructure and processing 537, 1 (2012). http://doi.org/10.1016/j.msea.2011.12.047
Abstract: Whereas deformation twinning is known to be an important deformation mechanism for hexagonal materials like magnesium and pure titanium, so far almost no literature exists on the twinning behaviour of the Ti-6Al-4V alloy. In this work it was shown that the activation of twinning as a deformation mechanism could have a pronounced effect on the mechanical behaviour of the Ti-6Al-4V alloy. This effect is even more pronounced under dynamic loading conditions. Transmission electron microscopy showed that only the {1 0 1 2}{1 0 1 1} tensile twin system was activated under certain loading conditions. Light-optical microscopy and electron backscatter diffraction data were afterwards used to experimentally determine the twin fractions. The importance of twinning for the texture evolution was also studied. It was shown that even small twin fractions can lead to distinct texture features, especially due to the discrete reorientation of the c-axes. The experimental results were compared to simulated results that were obtained with a viscoplastic self-consistent crystal plasticity code, after experimental validation that twinning can be reliably modelled as a unidirectional slip system. Although good agreement was obtained for the experimental and simulated stress-strain curves, the simulated results concerning twinning correlated well only on a qualitative basis as the simulated twin fractions were systematically higher than the experimental fractions. This seems to strengthen the hypothesis made by other research groups that complete grains might reorient by twinning. (C) 2011 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 3.094
Times cited: 35
DOI: 10.1016/j.msea.2011.12.047
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“In situ transmission electron microscopy of stress-induced martensite with focus on martensite twinning”. Tirry W, Schryvers D, Materials science and engineering: part A: structural materials: properties, microstructure and processing 481, 420 (2008). http://doi.org/10.1016/j.msea.2006.12.214
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.094
Times cited: 22
DOI: 10.1016/j.msea.2006.12.214
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“Linking a completely three-dimensional nanostrain to a structural transformation eigenstrain”. Tirry W, Schryvers D, Nature materials 8, 752 (2009). http://doi.org/10.1038/NMAT2488
Abstract: NiTi is one of the most popular shape-memory alloys, a phenomenon resulting from a martensitic transformation. Commercial NiTi-based alloys are often thermally treated to contain Ni4Ti3 precipitates. The presence of these precipitates can introduce an extra transformation step related to the so-called R-phase. It is believed that the strain field surrounding the precipitates, caused by the matrixprecipitate lattice mismatch, lies at the origin of this intermediate transformation step. Atomic-resolution transmission electron microscopy in combination with geometrical phase analysis is used to measure the elastic strain field surrounding these precipitates. By combining measurements from two different crystallographic directions, the three-dimensional strain matrix is determined from two-dimensional measurements. Comparison of the measured strain matrix to the eigenstrain of the R-phase shows that both are very similar and that the introduction of the R-phase might indeed compensate the elastic strain introduced by the precipitate.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 39.737
Times cited: 53
DOI: 10.1038/NMAT2488
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“Measuring strain fields and concentration gradients around Ni4Ti3 precipitates”. Schryvers D, Tirry W, Yang ZQ;, Materials science and engineering A: structural materials properties microstructure and processing 438, 485 (2006). http://doi.org/10.1016/j.msea.2006.02.166
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.094
Times cited: 35
DOI: 10.1016/j.msea.2006.02.166
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“Microstructural study of equiatomic PtTi martensite and the discovery of a new long-period structure”. Rotaru G-M, Tirry W, Sittner P, van Humbeeck J, Schryvers D, Acta materialia 55, 4447 (2007). http://doi.org/10.1016/j.actamat.2007.04.010
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 5.301
Times cited: 7
DOI: 10.1016/j.actamat.2007.04.010
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“Microstructure and defect characterization at interfaces in TiN/CrN multilayer coatings”. Major L, Tirry W, Van Tendeloo G, Surface and coatings technology 202, 6075 (2008). http://doi.org/10.1016/j.surfcoat.2008.07.005
Abstract: Microstructures of TiN/CrN multilayer coatings deposited on austenite steel (Cr Ni 18 8) by pulsed laser deposition (PLD) are characterized using transmission electron microscopy while their mechanical properties were assessed in a ball-on-disk test. All coatings have the same total thickness of about 1 ìm. The individual layers show a highly defective columnar structure, which is characterized by conventional electron microscopy (TEM) as well as by high resolution TEM. These techniques, combined with measurements of the local chemical composition through EDS prove that PLD allows to produce fully separated CrN and TiN layers. The friction, and consequently the wear, are lowered by increasing the total number of layers in the coating.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.589
Times cited: 23
DOI: 10.1016/j.surfcoat.2008.07.005
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“Microstructure of adiabatic shear bands in Ti6Al4V”. Peirs J, Tirry W, Amin-Ahmadi B, Coghe F, Verleysen P, Rabet L, Schryvers D, Degrieck J, Materials characterization 75, 79 (2013). http://doi.org/10.1016/j.matchar.2012.10.009
Abstract: Microstructural deformation mechanisms in adiabatic shear bands in Ti6Al4V are studied using traditional TEM and selected area diffraction, and more advanced microstructural characterisation techniques such as energy dispersive X-ray spectroscopy, high angle annular dark field STEM and conical dark field TEM. The shear bands under investigation are induced in Ti6Al4V samples by high strain rate compression of cylindrical and hat-shaped specimens in a split Hopkinson pressure bar setup. Samples from experiments interrupted at different levels of deformation are used to study the evolution of the microstructure in and nearby the shear bands. From the early stages of adiabatic shear band formation, TEM revealed strongly elongated equiaxed grains in the shear band. These band-like grains become narrower towards the centre of the band and start to fraction even further along their elongated direction to finally result in a nano-crystalline region in the core. In fully developed shear bands, twins and a needle-like martensite morphology are observed near the shear band.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.714
Times cited: 56
DOI: 10.1016/j.matchar.2012.10.009
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“A multi-scale characterization of deformation twins in Ti6Al4V sheet material deformed by simple shear”. Tirry W, Coghe F, Bouvier S, Gasperini M, Rabet L, Schryvers D, Materials science and engineering: part A: structural materials: properties, microstructure and processing 527, 4136 (2010). http://doi.org/10.1016/j.msea.2010.03.039
Abstract: Ti6Al4V sheet material is subjected to simple shear deformation with strain ratio's of 10%, 30% and 50%. Optical microscopy, transmission electron microscopy and electron backscatter diffraction techniques are applied to study the presence and morphology of deformation twins. Only the View the MathML source type of twins seems to be present with a volume fraction below 1%. These View the MathML source twins show a high density of basal stacking faults of the ABABACAC type identified using atomic resolution transmission electron microscopy. A resolved shear stress analysis shows that twins most often occur on those planes with the highest resolved shear stresses, but that the starting texture is not beneficial for the occurrence of twins. It is further suggested that a transitory strain hardening regime observed around 530 MPa might be related with the onset of twinning.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.094
Times cited: 20
DOI: 10.1016/j.msea.2010.03.039
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“Optimization of a FIB/SEM slice-and-view study of the 3D distribution of Ni4Ti3 precipitates in NiTi”. Cao S, Tirry W, van den Broek W, Schryvers D, Journal of microscopy 233, 61 (2009). http://doi.org/10.1111/j.1365-2818.2008.03095.x
Abstract: The 3D morphology and distribution of lenticular Ni4Ti3 precipitates in the austenitic B2 matrix of a binary Ni51Ti49 alloy has been investigated by a slice-and-view procedure in a dual-beam focused ion beam/scanning electron microscope system. Due to the weak contrast of the precipitates, proper imaging conditions need to be selected first to allow for semi-automated image treatment. Knowledgeable imaging is further needed to ensure that all variants of the precipitates are observed with equal probability, regardless of sample orientation. Finally, a volume ratio of 10.2% for the Ni4Ti3 precipitates could be calculated, summed over all variants, which yields a net composition of Ni50.27Ti49.73 for the matrix, leading to an increase of 125 degrees for the martensitic start temperature. Also, the expected relative orientation of the different variants of the precipitates could be confirmed.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 1.692
Times cited: 22
DOI: 10.1111/j.1365-2818.2008.03095.x
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“Quantitative determination of strain fields around Ni4Ti3 precipitates in NiTi”. Tirry W, Schryvers D, Acta materialia 53, 1041 (2005). http://doi.org/10.1016/j.actamat.2004.10.049
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 5.301
Times cited: 97
DOI: 10.1016/j.actamat.2004.10.049
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“Quantitative determination of the crystal structure of Ni4Ti3 precipitates”. Tirry W, Schryvers D, Jorissen K, Lamoen D, Materials science and engineering: part A: structural materials: properties, microstructure and processing 438, 517 (2006). http://doi.org/10.1016/j.msea.2006.02.063
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.094
Times cited: 7
DOI: 10.1016/j.msea.2006.02.063
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“Ni4Ti3 precipitates and their influence on the surrounding NiTi matrix”. Schryvers D, Tirry W, Yang Z, , 205 (2005)
Abstract: The properties of the shape memory behaviour of Ni-rich binary NiTi are strongly dependant on the thermal history of the material. In this respect the changing of transformation temperatures of the underlying martensitic transformation and the occurrence of multiple step transformations are the most important phenomena. Part of the explanation is found in the presence of Ni4Ti3 precipitates in the B2 matrix after particular heat treatments. The formation of these precipitates changes the Ni concentration of the matrix and induces a strain field, with both of these aspects expected to be of importance. In this work atomic resolution and analytical TEM (transmission electron microscopy) techniques are used to obtain quantitative information concerning these two main features. Furthermore, the known structure of Ni4Ti3 is refined by a least squares optimization of quantitative electron diffraction data. The high-resolution TEM results show that there are strains up to 2% in the matrix surrounding the precipitates and they gradually increase until a maximum is reached when moving away from the interface. Analytical results reveal a global decrease of Ni content in the matrix when sufficient precipitates are present and a gradient in their close vicinity. The refinement of the structure shows atomic displacements, thereby increasing our understanding of the shrinking of the precipitate lattice with respect to the matrix.
Keywords: P1 Proceeding; Electron microscopy for materials research (EMAT)
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“Twinning in pure Ti subjected to monotonic simple shear deformation”. Tirry W, Bouvier S, Benmhenni N, Hammami W, Habraken AM, Coghe F, Schryvers D, Rabet L, Materials characterization 72, 24 (2012). http://doi.org/10.1016/j.matchar.2012.07.001
Abstract: The aim of this paper is to provide a thorough study on the occurrence and importance of deformation twinning in simple shear deformed pure α-Ti. A statistically relevant inspection of the morphology of the deformation twins in relation to the applied strain/deformation is performed. The investigated microstructural aspects are the twin volume fraction, the twin thickness distribution and the resolved shear stress distribution on the twin plane. All these aspects are examined as a function of the twin types and two initial textures. Monotonic simple shear experiments are carried out for three different loading directions with respect to a direction linked to the initial crystallographic texture. EBSD and TEM observations reveal the presence of View the MathML source and View the MathML source twins. The statistical analysis reveals that View the MathML source and View the MathML source twins have a similar average thickness around 1.9 nm, but the View the MathML source twins show a far larger spread on their thickness and can grow to almost the size of the original parent grain. Correlation of the twin fractions with the RSS analysis shows that RSS is an acceptable method explaining the difference in twin fractions for different textures and orientations. A detailed analysis shows that View the MathML source twins occur in average with a smaller volume fraction but with a higher RSS, indicating they are more difficult to nucleate or grow compared to View the MathML source twinning. In general a higher RSS value on the twin plane is not connected to a higher twin thickness; only in the case of View the MathML source twins the highest RSS values show clearly thicker twins.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.714
Times cited: 25
DOI: 10.1016/j.matchar.2012.07.001
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