“Transmission electron microscopy investigation of microstructures in low-hysteresis alloys with special lattice parameters”. Delville R, Schryvers D, Zhang Z, James RD, Scripta materialia 60, 293 (2009). http://doi.org/10.1016/j.scriptamat.2008.10.025
Abstract: A sharp drop in hysteresis is observed for shape memory alloys satisfying the compatibility condition between austenite and martensite, i.e. ë2 = 1, where ë2 is the middle eigenvalue of the transformation strain matrix. The present work investigates the evolution of microstructure by transmission electron microscopy as the composition of the Ti50Ni50−xPdx system is systemically tuned to achieve the condition ë2 = 1. Changes in morphology, twinning density and twinning modes are reported along with twinless martensite and exact austenitemartensite interfaces.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 3.747
Times cited: 56
DOI: 10.1016/j.scriptamat.2008.10.025
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“Unit cell determination in CuZr martensite by EM and X-ray diffraction”. Schryvers D, Firstov GS, Seo JW, van Humbeeck J, Koval YN, Scripta materialia 36, 1119 (1997)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.747
Times cited: 76
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“Orientation relationship of the austenite-to-ferrite transformation in austenitic stainless steels due to dissolution corrosion in contact with liquid Pb-Bi eutectic”. Charalampopoulou E, Cautaerts N, Van der Donck T, Schryvers D, Lambrinou K, Delville R, Scripta materialia 167, 66 (2019). http://doi.org/10.1016/J.SCRIPTAMAT.2019.03.035
Abstract: The orientation relationship of an austenite-to-ferrite phase transformation in 316L stainless steels induced by the loss of austenite stabilizers resulting from the steel dissolution corrosion in liquid Pb-Bi eutectic was studied by means of electron backscatter diffraction. The misorientations at the austenite/ferrite interface were compared to the prevailing orientation relationship models in steels. The Pitsch orientation relationship model was found to be predominant, which is unusual for austenite-to-ferrite bulk transformations in steels. The nature of this particular transformation, which involves loss of steel alloying elements and the presence of an interfacial liquid metal layer, is discussed to explain this finding. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 3.747
Times cited: 3
DOI: 10.1016/J.SCRIPTAMAT.2019.03.035
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“Anomalous stress-strain behavior of NiTi shape memory alloy close to the border of superelastic window”. Wang X, Yao X, Schryvers D, Verlinden B, Wang G, Zhao G, Van Humbeeck J, Kustov S, Scripta Materialia 204, 114135 (2021). http://doi.org/10.1016/J.SCRIPTAMAT.2021.114135
Abstract: In this work, we report an anomalous phenomenon on superelastic cycling of NiTi shape memory alloys when deforming at the temperature close to the border of superelastic window. New unexpected effects are found-(i) critical stress for inducing martensite transformation during the second loading cycle is higher than that of the first cycle; ( ii ) the plateau stress of the second cycle decreases to the original level when the strain overcomes the limit of the first cycle; ( iii ) transition from good superelasticity in the first cycle to fully irreversible strain in the second. We propose that defects generated during the first superelastic cycle close to the border of superelastic window impede following stress-induced martensitic transformations, leading to the increase of critical stress beyond yield stress of the B2 matrix, and thus functional fatigue of NiTi alloys. (c) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 3.747
DOI: 10.1016/J.SCRIPTAMAT.2021.114135
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“HREM investigation of martensite precursor effects and stacking sequences in Ni-Mn-Ti alloys”. Schryvers D, Lahjouji DE, Slootmaekers B, Potapov PL, Scripta metallurgica et materialia 35, 1235 (1996). http://doi.org/10.1016/1359-6462(96)00271-0
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.224
Times cited: 2
DOI: 10.1016/1359-6462(96)00271-0
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“Electron microscopy study of the formation of Ni5Al3 in a Ni62.5Al37.5 B2 alloy: 1: precipitation and growth”. Schryvers D, Ma Y, Toth L, Tanner LE, Acta metallurgica et materialia 43, 4045 (1995). http://doi.org/10.1016/0956-7151(95)00101-Z
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 27
DOI: 10.1016/0956-7151(95)00101-Z
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“Electron microscopy study of the formation of Ni5Al3 in a Ni62.5Al37.5 B2 alloy: 2: plate crystallography”. Schryvers D, Ma Y, Toth L, Tanner LE, Acta metallurgica et materialia 43, 4057 (1995). http://doi.org/10.1016/0956-7151(95)00102-2
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 11
DOI: 10.1016/0956-7151(95)00102-2
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“HREM and ED study of the displacive transformation of the Ni2Al phase in a Ni65Al35 alloy and associated with the martensitic transformation”. Muto S, Schryvers D, Merk N, Tanner LE, Acta metallurgica et materialia 41, 2377 (1993)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 31
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“On the nucleation mechanism of {112} <, 111 >, mechanical twins in as-quenched beta metastable Ti-12 wt.% Mo alloy”. Marteleur M, Idrissi H, Amin-Ahmadi B, Prima F, Schryvers D, Jacques PJ, Materialia 7, Unsp 100418 (2019). http://doi.org/10.1016/J.MTLA.2019.100418
Abstract: Recently developed beta-metastable Ti grades take advantage of the simultaneous activation of TRIP and TWIP effects for enhancing their work hardening rate. However, the role of each plasticity mechanism on the macroscopic mechanical response is still unclear. In this work, the nucleation mechanism of the first activated plasticity mechanism, namely {112} < 111 > twinning, was investigated. Firstly, post-mortem TEM analysis showed that twins nucleate on pre-existing microstructural defects such as thermal jogs with the zonal dislocation mechanism. The precipitation of the omega phase on twin boundaries has been observed, as well as the emission of numerous dislocations from super-jogs present in these twin boundaries. It is also shown that {112} < 111 > twins act as effective dislocation sources for the subsequent plasticity mechanisms such as beta -> alpha '' martensitic transformation and {332} < 111 > twinning. Secondly, in situ TEM tensile testing of the investigated Ti grade highlighted the primary role of the initial defect configuration present in the microstructure. It is shown that twins cannot nucleate without the presence of specific defects allowing the triggering of the dislocation decomposition needed for the twinning mechanism highlighted in investigated bulk samples.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
DOI: 10.1016/J.MTLA.2019.100418
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“Towards ductilization of high strength 7XXX aluminium alloys via microstructural modifications obtained by friction stir processing and heat treatments”. Lezaack MB, Hannard F, Zhao L, Orekhov A, Adrien J, Miettinen A, Idrissi H, Simar A, Materialia 20, 101248 (2021). http://doi.org/10.1016/J.MTLA.2021.101248
Abstract: High strength 7XXX aluminium series reach exceptional strength, higher than all other industrial aluminium alloys. However, they suffer from a lack of ductility compared to softer series. This work presents a procedure to improve the ductility of 7475 Al alloy in high strength condition, reaching a true fracture strain of 70% at full 500 MPa T6 yield strength. Using friction stir processing (FSP) and post-FSP heat treatments, 100% of industrial rolled material T6 yield stress is maintained but a 180% increase in fracture strain is measured for the processed material. This ductility improvement is studied by in-situ synchrotron X-ray tomography and is explained by the reduction of intermetallic particles size and the homogenization of their spatial distribution. Furthermore, the microstructure after FSP shows equiaxed refined grains which favour crack deviation as opposed to large cracks parallel to the elongated coarse grains in rolled plate. These results are paving the way to better formability and crashworthiness of 7XXX alloys.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
DOI: 10.1016/J.MTLA.2021.101248
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