The Experts below are selected from a list of 2007 Experts worldwide ranked by ideXlab platform
Hussein M. Zbib - One of the best experts on this subject based on the ideXlab platform.
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the effect of layer thickness ratio on the plastic deformation mechanisms of nanoindented ti tin nanolayered composite
Computational Materials Science, 2018Co-Authors: Wei Yang, Georges Ayoub, I Salehinia, Bilal Mansoor, Hussein M. ZbibAbstract:Abstract Molecular dynamics simulations were performed to identify the underlying deformation mechanisms controlling the plastic behavior of nanoindented nanoscale multilayered Ti/TiN. MD simulations were conducted on pure Ti and pure TiN as well as on four different layer-thickness ratios of Ti/TiN multilayers, Ti:TiN = 1, 2.5, 4, and 7.5. The Ti layer thickness varied from 2 nm to 15 nm while the TiN layer thickness is kept constant of 2 nm. The plastic deformation of nanoindented pure Ti was dominated by the formation of Dislocation loops resulting from basal partial Dislocations, while very few Perfect Dislocations that tie Dislocation loops together were observed. The plastic deformation of nanoindented pure TiN was controlled by the activation of Perfect Dislocation propagation along the ( 1 1 1 ) plane that dissociates into two partials. Depending on the thickness ratio, either Dislocation pile-up or single Dislocation crossing through the interface was the controlling plastic deformation mechanism of nanoindented Ti/TiN multilayers. For metal layer thicknesses above 5 nm, significant Dislocation pile-ups were observed at the interface of the multi-layered samples. The Ti/TiN multilayer with a thickness ratio of 1:1 with individual layer thickness of 2 nm exhibited the highest strain-hardening rate. At this length scale, the activation of Dislocation sources requires very high stresses, and the single Dislocation crossing process is the most dominant deformation mechanism. The initiation of plasticity in the TiN layer occurs at a high level of stress since there is no Dislocation pile-up at the interface.
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deformation mechanisms in ti tin multilayer under compressive loading
Acta Materialia, 2017Co-Authors: W Yang, I Salehinia, Georges Ayoub, Bilal Mansoor, Hussein M. ZbibAbstract:Abstract The promising mechanical, physical and chemical properties of nano-scale metal/ceramic multilayers (MCMs) are of high interest for extreme environment applications. Understanding the plastic deformation mechanisms and the variables affecting those properties is therefore essential. The interface characteristics and the plastic deformation mechanisms under compressive loading in a Ti/TiN multilayer with a semi-coherent interface are numerically investigated. The interface structure of the Ti/TiN interface and the interface misfit Dislocation were characterized using molecular dynamic simulations combined with atomically informed Frank-Bilby method. Three possible atomic stacking interface structures are identified according to the crystallographic analysis of the interface. Upon relaxation, large interface areas are occupied with the energetically stable configuration. Furthermore, the higher energy stacking are transformed into misfit Dislocations or Dislocation nodes. The molecular dynamic compressive stress strain response of the Ti/TiN multilayers exhibited three distinctive peaks. The first peak was generated by the Dislocation dissociation of Perfect Dislocation into pairs of partials Dislocation around extended nodes region at the interface. Upon further compression the second peak, identified as the first yielding, resulted from the activation of pyramidal slip planes in the Ti layer. Finally, a third peak identified as the second yielding, occurred when Dislocation nucleated/transmitted in/into the TiN layer.
I Salehinia - One of the best experts on this subject based on the ideXlab platform.
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the effect of layer thickness ratio on the plastic deformation mechanisms of nanoindented ti tin nanolayered composite
Computational Materials Science, 2018Co-Authors: Wei Yang, Georges Ayoub, I Salehinia, Bilal Mansoor, Hussein M. ZbibAbstract:Abstract Molecular dynamics simulations were performed to identify the underlying deformation mechanisms controlling the plastic behavior of nanoindented nanoscale multilayered Ti/TiN. MD simulations were conducted on pure Ti and pure TiN as well as on four different layer-thickness ratios of Ti/TiN multilayers, Ti:TiN = 1, 2.5, 4, and 7.5. The Ti layer thickness varied from 2 nm to 15 nm while the TiN layer thickness is kept constant of 2 nm. The plastic deformation of nanoindented pure Ti was dominated by the formation of Dislocation loops resulting from basal partial Dislocations, while very few Perfect Dislocations that tie Dislocation loops together were observed. The plastic deformation of nanoindented pure TiN was controlled by the activation of Perfect Dislocation propagation along the ( 1 1 1 ) plane that dissociates into two partials. Depending on the thickness ratio, either Dislocation pile-up or single Dislocation crossing through the interface was the controlling plastic deformation mechanism of nanoindented Ti/TiN multilayers. For metal layer thicknesses above 5 nm, significant Dislocation pile-ups were observed at the interface of the multi-layered samples. The Ti/TiN multilayer with a thickness ratio of 1:1 with individual layer thickness of 2 nm exhibited the highest strain-hardening rate. At this length scale, the activation of Dislocation sources requires very high stresses, and the single Dislocation crossing process is the most dominant deformation mechanism. The initiation of plasticity in the TiN layer occurs at a high level of stress since there is no Dislocation pile-up at the interface.
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deformation mechanisms in ti tin multilayer under compressive loading
Acta Materialia, 2017Co-Authors: W Yang, I Salehinia, Georges Ayoub, Bilal Mansoor, Hussein M. ZbibAbstract:Abstract The promising mechanical, physical and chemical properties of nano-scale metal/ceramic multilayers (MCMs) are of high interest for extreme environment applications. Understanding the plastic deformation mechanisms and the variables affecting those properties is therefore essential. The interface characteristics and the plastic deformation mechanisms under compressive loading in a Ti/TiN multilayer with a semi-coherent interface are numerically investigated. The interface structure of the Ti/TiN interface and the interface misfit Dislocation were characterized using molecular dynamic simulations combined with atomically informed Frank-Bilby method. Three possible atomic stacking interface structures are identified according to the crystallographic analysis of the interface. Upon relaxation, large interface areas are occupied with the energetically stable configuration. Furthermore, the higher energy stacking are transformed into misfit Dislocations or Dislocation nodes. The molecular dynamic compressive stress strain response of the Ti/TiN multilayers exhibited three distinctive peaks. The first peak was generated by the Dislocation dissociation of Perfect Dislocation into pairs of partials Dislocation around extended nodes region at the interface. Upon further compression the second peak, identified as the first yielding, resulted from the activation of pyramidal slip planes in the Ti layer. Finally, a third peak identified as the second yielding, occurred when Dislocation nucleated/transmitted in/into the TiN layer.
Georges Ayoub - One of the best experts on this subject based on the ideXlab platform.
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the effect of layer thickness ratio on the plastic deformation mechanisms of nanoindented ti tin nanolayered composite
Computational Materials Science, 2018Co-Authors: Wei Yang, Georges Ayoub, I Salehinia, Bilal Mansoor, Hussein M. ZbibAbstract:Abstract Molecular dynamics simulations were performed to identify the underlying deformation mechanisms controlling the plastic behavior of nanoindented nanoscale multilayered Ti/TiN. MD simulations were conducted on pure Ti and pure TiN as well as on four different layer-thickness ratios of Ti/TiN multilayers, Ti:TiN = 1, 2.5, 4, and 7.5. The Ti layer thickness varied from 2 nm to 15 nm while the TiN layer thickness is kept constant of 2 nm. The plastic deformation of nanoindented pure Ti was dominated by the formation of Dislocation loops resulting from basal partial Dislocations, while very few Perfect Dislocations that tie Dislocation loops together were observed. The plastic deformation of nanoindented pure TiN was controlled by the activation of Perfect Dislocation propagation along the ( 1 1 1 ) plane that dissociates into two partials. Depending on the thickness ratio, either Dislocation pile-up or single Dislocation crossing through the interface was the controlling plastic deformation mechanism of nanoindented Ti/TiN multilayers. For metal layer thicknesses above 5 nm, significant Dislocation pile-ups were observed at the interface of the multi-layered samples. The Ti/TiN multilayer with a thickness ratio of 1:1 with individual layer thickness of 2 nm exhibited the highest strain-hardening rate. At this length scale, the activation of Dislocation sources requires very high stresses, and the single Dislocation crossing process is the most dominant deformation mechanism. The initiation of plasticity in the TiN layer occurs at a high level of stress since there is no Dislocation pile-up at the interface.
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deformation mechanisms in ti tin multilayer under compressive loading
Acta Materialia, 2017Co-Authors: W Yang, I Salehinia, Georges Ayoub, Bilal Mansoor, Hussein M. ZbibAbstract:Abstract The promising mechanical, physical and chemical properties of nano-scale metal/ceramic multilayers (MCMs) are of high interest for extreme environment applications. Understanding the plastic deformation mechanisms and the variables affecting those properties is therefore essential. The interface characteristics and the plastic deformation mechanisms under compressive loading in a Ti/TiN multilayer with a semi-coherent interface are numerically investigated. The interface structure of the Ti/TiN interface and the interface misfit Dislocation were characterized using molecular dynamic simulations combined with atomically informed Frank-Bilby method. Three possible atomic stacking interface structures are identified according to the crystallographic analysis of the interface. Upon relaxation, large interface areas are occupied with the energetically stable configuration. Furthermore, the higher energy stacking are transformed into misfit Dislocations or Dislocation nodes. The molecular dynamic compressive stress strain response of the Ti/TiN multilayers exhibited three distinctive peaks. The first peak was generated by the Dislocation dissociation of Perfect Dislocation into pairs of partials Dislocation around extended nodes region at the interface. Upon further compression the second peak, identified as the first yielding, resulted from the activation of pyramidal slip planes in the Ti layer. Finally, a third peak identified as the second yielding, occurred when Dislocation nucleated/transmitted in/into the TiN layer.
Bruno C De Cooman - One of the best experts on this subject based on the ideXlab platform.
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micro plasticity of medium mn austenitic steel Perfect Dislocation plasticity and deformation twinning
Acta Materialia, 2017Co-Authors: Javad Mola, Chang Yeol Oh, Bruno C De CoomanAbstract:Abstract The micro-scale plastic deformation behavior of an austenitic Fe-1.2%C-7.0%Mn (in wt%) steel was studied by means of nano-indentation and in situ compression of micro-pillars with selected crystallographic orientations. Transmission electron microscopy analysis reveals that the partial Dislocation mediated twinning is preferred in a [001]-oriented single grain under compression. Twinning leads to large strain bursts during the nano-indentation and the micro-pillar compression. Perfect Dislocation slip is the dominant deformation mechanism in a [111]-oriented single grain under compression. The observations offer strong support for the hypothesis that deformation twinning is a plasticity enhancing mechanism activated during the deformation of medium Mn steel.
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size and orientation effects in partial Dislocation mediated deformation of twinning induced plasticity steel micro pillars
Acta Materialia, 2015Co-Authors: Won Seok Choi, Bruno C De Cooman, Stefanie Sandlobes, Dierk RaabeAbstract:Abstract Bulk and micro-pillar single crystals were used to investigate the twinning-induced plasticity mechanism in austenitic Fe-22 wt%Mn-0.6 wt%C TWIP steel. Compression of micro-pillars oriented either for deformation-induced twinning or for Perfect Dislocation glide was carried out for pillars with diameters in the range of 600 nm to 4 μm. The same size dependence of the critical resolved shear stress was observed for both orientations. The critical micro-pillar diameter for size-independent plasticity was approximately 7.6 μm. Partial Dislocation-mediated formation of twins and e-martensite was observed in micro-pillars oriented for twinning by transmission electron microscopy. The elastic–plastic transition in micro-pillars oriented for deformation twinning did not involve twinning, and Dislocation–Dislocation interactions were a necessary precondition for twin formation.
Bilal Mansoor - One of the best experts on this subject based on the ideXlab platform.
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the effect of layer thickness ratio on the plastic deformation mechanisms of nanoindented ti tin nanolayered composite
Computational Materials Science, 2018Co-Authors: Wei Yang, Georges Ayoub, I Salehinia, Bilal Mansoor, Hussein M. ZbibAbstract:Abstract Molecular dynamics simulations were performed to identify the underlying deformation mechanisms controlling the plastic behavior of nanoindented nanoscale multilayered Ti/TiN. MD simulations were conducted on pure Ti and pure TiN as well as on four different layer-thickness ratios of Ti/TiN multilayers, Ti:TiN = 1, 2.5, 4, and 7.5. The Ti layer thickness varied from 2 nm to 15 nm while the TiN layer thickness is kept constant of 2 nm. The plastic deformation of nanoindented pure Ti was dominated by the formation of Dislocation loops resulting from basal partial Dislocations, while very few Perfect Dislocations that tie Dislocation loops together were observed. The plastic deformation of nanoindented pure TiN was controlled by the activation of Perfect Dislocation propagation along the ( 1 1 1 ) plane that dissociates into two partials. Depending on the thickness ratio, either Dislocation pile-up or single Dislocation crossing through the interface was the controlling plastic deformation mechanism of nanoindented Ti/TiN multilayers. For metal layer thicknesses above 5 nm, significant Dislocation pile-ups were observed at the interface of the multi-layered samples. The Ti/TiN multilayer with a thickness ratio of 1:1 with individual layer thickness of 2 nm exhibited the highest strain-hardening rate. At this length scale, the activation of Dislocation sources requires very high stresses, and the single Dislocation crossing process is the most dominant deformation mechanism. The initiation of plasticity in the TiN layer occurs at a high level of stress since there is no Dislocation pile-up at the interface.
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deformation mechanisms in ti tin multilayer under compressive loading
Acta Materialia, 2017Co-Authors: W Yang, I Salehinia, Georges Ayoub, Bilal Mansoor, Hussein M. ZbibAbstract:Abstract The promising mechanical, physical and chemical properties of nano-scale metal/ceramic multilayers (MCMs) are of high interest for extreme environment applications. Understanding the plastic deformation mechanisms and the variables affecting those properties is therefore essential. The interface characteristics and the plastic deformation mechanisms under compressive loading in a Ti/TiN multilayer with a semi-coherent interface are numerically investigated. The interface structure of the Ti/TiN interface and the interface misfit Dislocation were characterized using molecular dynamic simulations combined with atomically informed Frank-Bilby method. Three possible atomic stacking interface structures are identified according to the crystallographic analysis of the interface. Upon relaxation, large interface areas are occupied with the energetically stable configuration. Furthermore, the higher energy stacking are transformed into misfit Dislocations or Dislocation nodes. The molecular dynamic compressive stress strain response of the Ti/TiN multilayers exhibited three distinctive peaks. The first peak was generated by the Dislocation dissociation of Perfect Dislocation into pairs of partials Dislocation around extended nodes region at the interface. Upon further compression the second peak, identified as the first yielding, resulted from the activation of pyramidal slip planes in the Ti layer. Finally, a third peak identified as the second yielding, occurred when Dislocation nucleated/transmitted in/into the TiN layer.