Characterization of phases formed in the iron carbide process by X-ray diffraction, mossbauer, X-ray photoelectron spectroscopy, and raman spectroscopy analyses

Iron carbide was prepared by iron ore reduction and iron cementation using Ar-H₂-CH₄ gas mixture with and without sulfur. Phases formed in the reduction/cementation process were examined by X-ray diffraction (XRD), Mossbauer, and Raman spectroscopy. The sample surface was also analyzed by X-ray photoelectron spectroscopy (XPS). XRD and Mossbauer analyses showed that iron oxide was first reduced to metallic iron, and then, metallic iron was carburized to cementite. Addition of a small amount of H₂S to the reaction gas retarded the cementite formation but made the cementite more stable. XPS analysis showed that the surface of samples converted to iron carbide using sulfurcontaining gas consisted of mainly Fe₃C and a small amount of graphitic carbon. Raman spectra of a sample produced in the iron carbide process showed the G and D bands, which are characteristic for carbon-carbon bonds. The intensity ratio of G/D bands depended on the sulfur content in the reducing/carburizing gas.     

Observation of cold-rolling texture and partially recrystallized texture in polycrystalline 3 pct Si-Fe by high-resolution electron backscattered diffraction

Cold-rolling texture and partially recrystallized texture of polycrystalline 3 pct Si-Fe were investigated using high-resolution electron backscattered diffraction (EBSD) method. From the measurement on a deformed grain with {211}〈011〉∼{111}〈011〉 orientations, deformation bands with {12 4 1}〈014〉 orientation were found. It turned out that the orientation rotation relationship between deformation bands and surrounding deformed grain can be explained by the activation of the slip system, which has a common slip plane with an adjacent grain. Oriented nucleation of recrystallized grains with {12 4 1}〈014〉 orientation was observed in a deformed grain with {211}〈011〉∼{111}〈011〉 orientation. Exactly the same orientation relationship that was observed between deformed grain and the deformation bands was also observed between the deformed grain and the recrystallized grain. A hypothesis that recrystallization nuclei are generated directly from the deformation bands formed by an activation of the slip system that has a common slip plane of neighboring deformed grains was proposed from the present experimental results.     

The significance of task significance: Job performance effects, relational mechanisms, and boundary conditions.

Does task significance increase job performance? Correlational designs and confounded manipulations have prevented researchers from assessing the causal impact of task significance on job performance. To address this gap, 3 field experiments examined the performance effects, relational mechanisms, and boundary conditions of task significance. In Experiment 1, fundraising callers who received a task significance intervention increased their levels of job performance relative to callers in 2 other conditions and to their own prior performance. In Experiment 2, task significance increased the job dedication and helping behavior of lifeguards, and these effects were mediated by increases in perceptions of social impact and social worth. In Experiment 3, conscientiousness and prosocial values moderated the effects of task significance on the performance of new fundraising callers. The results provide fresh insights into the effects, relational mechanisms, and boundary conditions of task significance, offering noteworthy implications for theory, research, and practice on job design, social information processing, and work motivation and performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Investigation of the structure and composition of a {111} incoherent Zr/ZrN interface containing ledges by high-resolution transmission electron microscopy, image simulation, electron energy-loss spectroscopy, energy-filtering transmission electron microscopy, and near-coincidence-site analysis

Investigation of the atomic structure of a Zr/ZrN interface shows that it is a type-3 incoherent interface (i.e., high-index orientation relationship with a low-index interface plane in only one phase), as determined from conventional transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) images, image simulations, and near-coincidence-site atomic modeling of the interface. Long facets and atomic ledges several {111}_ZrN planes high form at the interface, indicating that such features cannot be used as criteria to define partial coherency at interfaces. These results also indicate that ledgewise growth is possible during the phase transformation from Zr to ZrN. Composition profiles taken across the interface using energy-filtering TEM and the N K-edge show that the composition changes abruptly at the interface, in accord with the structural transformation. Simulation results on an inclined Zr/ZrN interface indicate that it is possible to judge whether an interface is inclined and faceted at the same time. A rough interface can look faceted in a HRTEM image due to projection effects, but only under a very strict set of conditions. Conversely, an interface cannot be faceted if it looks rough in an HRTEM image. This article is based on a presentation made in the “Hume-Rothery Symposium on Structure and Diffusional Growth Mechanisms of Irrational Interphase Boundaries,” which occurred during the TMS Winter meeting, March 15–17, 2004, in Charlotte, NC, under the auspices of the TMS Alloy Phases Committee and the co-sponsorship of the TMS-ASM Phase Transformations Committee.     

Investigation of the structure and composition of a {111} incoherent Zr/ZrN interface containing ledges by high-resolution transmission electron microscopy, image simulation, electron energy-loss spectroscopy, energy-filtering transmission electron microscopy, and near-coincidence-site analysis

Investigation of the atomic structure of a (111) Zr/ZrN interface shows that it is a type-3 incoherent interface (i.e., high-index orientation relationship with a low-index interface plane in only one phase), as determined from conventional transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) images, image simulations, and near-coincidence-site atomic modeling of the interface. Long facets and atomic ledges several {111}_ZrN planes high form at the interface, indicating that such features cannot be used as criteria to define partial coherency at interfaces. These results also indicate that ledgewise growth is possible during the phase transformation from Zr to ZrN. Composition profiles taken across the interface using energy-filtering TEM and the N K-edge show that the composition changes abruptly at the interface, in accord with the structural transformation. Simulation results on an inclined (111) Zr/ZrN interface indicate that it is possible to judge whether an interface is inclined and faceted at the same time. A rough interface can look faceted in a HRTEM image due to projection effects, but only under a very strict set of conditions. Conversely, an interface cannot be faceted if it looks rough in an HRTEM image. This article is based on a presentation made in the “Hume-Rothery Symposium on Structure and Diffusional Growth Mechanisms of Irrational Interphase Boundaries,” which occurred during the TMS Winter meeting, March 15–17, 2004, in Charlotte, NC, under the auspices of the TMS Alloy Phases Committee and the co-sponsorship of the TMS-ASM Phase Transformations Committee.     

Investigation of the structure and composition of a {111} incoherent Zr/ZrN interface containing ledges by high-resolution transmission electron microscopy, image simulation, electron energy-loss spectroscopy, energy-filtering transmission electron microscopy, and near-coincidence-site analysis

Investigation of the atomic structure of a Zr/ZrN interface shows that it is a type-3 incoherent interface (i.e., high-index orientation relationship with a low-index interface plane in only one phase), as determined from conventional transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) images, image simulations, and near-coincidence-site atomic modeling of the interface. Long facets and atomic ledges several {111}_ZrN planes high form at the interface, indicating that such features cannot be used as criteria to define partial coherency at interfaces. These results also indicate that ledgewise growth is possible during the phase transformation from Zr to ZrN. Composition profiles taken across the interface using energy-filtering TEM and the N K-edge show that the composition changes abruptly at the interface, in accord with the structural transformation. Simulation results on an inclined Zr/ZrN interface indicate that it is possible to judge whether an interface is inclined and faceted at the same time. A rough interface can look faceted in a HRTEM image due to projection effects, but only under a very strict set of conditions. Conversely, an interface cannot be faceted if it looks rough in an HRTEM image. This article is based on a presentation made in the “Hume-Rothery Symposium on Structure and Diffusional Growth Mechanisms of Irrational Interphase Boundaries,” which occurred during the TMS Winter meeting, March 15–17, 2004, in Charlotte, NC, under the auspices of the TMS Alloy Phases Committee and the co-sponsorship of the TMS-ASM Phase Transformations Committee.