Interdiffusion structures and paths for multiphase Fe-Ni-Al diffusion couples at 1000 °C

Diffusion studies were carried out in the Fe-Ni-Al system at 1000 °C using solid-solid diffusion couples assembled with β (B2), γ (fcc) single phase, and (β + γ) two-phase alloys. The diffusion couples were encapsulated in quartz tubes under vacuum and annealed for 48 hours. The diffusion structures were examined by optical and scanning electron microscopy. For all β vs (β + γ) couples, growth of the β phase was observed as the (β + γ) two-phase region recessed with the dissolution of the γ phase. For multiphase couples assembled with two (β + γ) terminal alloys, demixing of the (β + γ) two-phase alloys occurred with the formation of single-phase β and γ layers. The development of an interphase boundary between the (β + β′) two-phase region and the γ phase is reported for the first time for a Fe-Ni-Al diffusion couple assembled with single-phase, β, and γ terminal alloys. Various diffusion structures for the couples were related to their diffusion paths constructed from concentration profiles determined by electron probe microanalysis. Interdiffusion fluxes of individual components were determined directly from the experimental concentration profiles and examined in light of diffusional interactions and the development of zero-flux planes and flux reversals. In addition, the boundaries for the miscibility gap between the ordered β and disordered β′ phases of the Fe-Ni-Al system at 1000 °C were determined with the aid of diffusion couples that developed β and β′ phases in the diffusion zone

Improving the Applicability of Environmental Scanning Systems: State of the Art and Future Research

Part 5: Future SubjectsInternational audienceThe 2008/2009 economic crisis provided a sustainable impulse for improving environmental scanning systems (ESS). Although a rich body of know-ledge exists, concepts are not often used in practice. This article contributes a literature review addressing six findings for ESS design to become more applicable than the state of the art. They are structured by the elements of information systems (IS) design theories. Addressing the lack of a sound requirements analysis, our first finding proposes 360-degree ESS for executives’ "managing a company" task and presents how to select just the most important scanning areas to keep focus. Three other findings cover the IS model perspective focusing on a better "grasp" of weak signals: define concrete indicators and use IT to identify relevant cause-effective-chains, leverage IT to automate day-to-day routines and monitor the variety of indicators’ movements, and—as a fourth finding—leverage expert experience with an impact matrix and translate indicators’ impact into a balanced opportunity-and-threat portfolio. From the methods perspective on ESS, we propose to more closely incorporate scanning results into executives’ decision-making process by generating scenarios from a set of environment assumptions as well as to use retrospective controls to continuously update the ESS and collaborate to share the scanning findings day-to-day