Studies of the influence of alloying elements on the growth of ferrite from austenite under decarburization conditions: Fe-C-Nl alloys

We have evaluated controlled decarburization as a method for probing the effect of alloying elements on ferrite growth from austenite. The technique permits the exploration of longer-time ferrite layer growth; it minimizes the effects of interface structure on ferrite growth; and it permits the isolation of the effects of temperature and alloying element concentration on ferrite/austenite interface motion. The study of the decarburization of initially homogeneous Fe-C-Ni alloys was complemented by experiments using specimens with a controlled nickel concentration gradient. Although the decarburization method yields consistent results at longer times, it is found to be less appropriate for the study of initial ferrite growth. Nucleation in the gas/solid interface region, coupled with uncertainties about the precise time of decarburization, leads to large relative errors at the earliest times. For these reasons, the method is considered a valuable complement to studies based on precipitation boundary conditions. This article is based on a presentation given in the symposium “The Effects of Alloying Elements on the Gamma to Alpha Transformation in Steels,” October 6, 2002, at the TMS Fall Meeting in Columbus, Ohio, under the auspices of the McMaster Centre for Steel Research and the TMS-ASM Phase Transformations Committee.     

Geolocation and pointing accuracy analysis for the WindSat sensor

Geolocation and pointing accuracy analyses of the WindSat flight data are presented. The two topics were intertwined in the flight data analysis and will be addressed together. WindSat has no unusual geolocation requirements relative to other sensors, but its beam pointing knowledge accuracy is especially critical to support accurate polarimetric radiometry. Pointing accuracy was improved and verified using geolocation analysis in conjunction with scan bias analysis. Two methods were needed to properly identify and differentiate between data time tagging and pointing knowledge errors. Matchups comparing coastlines indicated in imagery data with their known geographic locations were used to identify geolocation errors. These coastline matchups showed possible pointing errors with ambiguities as to the true source of the errors. Scan bias analysis of U, the third Stokes parameter, and of vertical and horizontal polarizations provided measurement of pointing offsets resolving ambiguities in the coastline matchup analysis. Several geolocation and pointing bias sources were incrementally eliminated resulting in pointing knowledge and geolocation accuracy that met all design requirements.     

Edge-to-edge plane matching as a criterion for interphase boundaries of low energy

As demonstrated by Aaronson and his colleagues over five decades or so, the structure, energy, and dynamic response of interphase boundaries in metallic systems are strongly correlated. It has also become clear that very few, if any, solid/solid transformation interfaces can be considered truly “incoherent.” Most treatments of the geometry of irrational interfaces (facet planes) have focused on the density of coincidence sites or near-coincidence sites (NCS); this naturally involves consideration of the matching of densely packed atomic planes lying parallel to the facet. Edge-to-edge plane matching represents an alternative and, perhaps, more general approach to the geometry of transformation interfaces. For diffusional transformations, growth ledges are required to displace and reproduce the structure of the facet plane; their geometrical properties are distinct from those of the interfacial facets. The role of local thermodynamic driving force in determining the migration mode is assessed. Several recent observations of the transient faceting of irrational interfaces, for which the density of NCS is relatively low, have stimulated considerations of the significance of the invariant-line condition and of edge-to-edge plane matching as criteria for local minima in interfacial free energy. 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.     

Modeling of the dynamics of transient liquid films in ternary systems

The presence of a concentration gradient across a thin liquid film leads to the phenomenon of isothermal liquid film migration (LFM). In most cases, the concentration gradient is due to coherency stresses, and the migration of the liquid film results in the relaxation of these stresses. It is also possible to envisage cases in which LFM occurs as a result of chemical solubility differences between stable and metastable phases. Both situations are examined in this contribution with special emphasis on the effect of adding a second solute element to the liquid phase. The kinetics of LFM is examined as a function of the initial liquid concentration and the ratio of the solute diffusion coefficients in a model coherency-driven ternary system. The growth of the Γ₂ inside δ particles in the Zn-Fe-Al system is presented as a possible example of chemically driven LFM. This article was presented at the Multicomponent-Multiphase Diffusion Symposium in Honor of Mysore A. Dayananda, which was held during TMS 2006, the 135th Annual Meeting and Exhibition, March 12–16, 2006, in San Antonio, TX. The symposium was organized by Yongho Sohn of University of Central Florida, Carelyn E. Campbell of National Institute of Standards and Technology, Richard D. Sisson, Jr., of Worcester Polytechnic Institute, and John E. Morral of Ohio State University.     

Self-Consistent Model for Planar Ferrite Growth in Fe-C-X Alloys

A self-consistent model for non-partitioning planar ferrite growth from alloyed austenite is presented. The model captures the evolution with time of interfacial contact conditions for substitutional and interstitial solutes. Substitutional element solute drag is evaluated in terms of the dissipation of free energy within the interface, and an estimate is provided for the rate of buildup of the alloying element “spike” in austenite. The transport of the alloying elements within the interface region is modeled using a discrete-jump model, while the bulk diffusion of C is treated using a standard continuum treatment. The model is validated against ferrite precipitation and decarburization kinetics in the Fe-Ni-C, Fe-Mn-C, and Fe-Mo-C systems.     

58—A STUDY OF NEEDLE ACTION DURING NEEDLE-PUNCHING

Photographs produced by still and ciné techniques are presented to illustrate various aspects of needle action during needle-punching with a loom operating at 240 cycles/min. Complete loom cycles were studied in addition to isolated events. It appears that some fibre extension occurs during reorientation along with the slippage, which allows fibre movement. This study also illustrates how a stitched structure can be produced on the base of needled fabric under certain production conditions and that needle points assist in fibre reorientation.     

"Teaching about animal research in psychology": Erratum.

Reports an error in the original article by M. Domjan and J. E. Purdy (American Psychologist, 1996 [Jul], Vol 51[7], 736–737). Portions of the text were inadvertently omitted in the production process; the comment is presented in its entirety. (The following abstract of this article originally appeared in PA, Vol 83:32272.). Responds to P. F. Cunningham's (see record 83:32271) and S. D. Gosling's (see record 1995-45383-001) study of the acknowledgment of contributions of animal experimentation in leading introductory psychology textbooks. The authors agree with Gosling that the primary goal of the general psychology course is to facilitate the students' understanding of psychology and that animal research is not presented in an educationally effective fashion in general psychology textbooks. However, it is argued that students need to know not only the conclusions of research but also something about how the research was conducted. In response to Cunningham's contention that psychology instructors will have to address why research animals are kept under stressful laboratory conditions, the authors note that psychology experiments typically do not involve deadly diseases or experimental pathologies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Extracting Behavioral Data from Physical Descriptions of MEMS for Simulation

The work described here deals with the problems of modeling and simulation for MEMS devices. The eventual goal is to produce a top-down MEMS design system similar to today’s powerful VLSI design systems. In this work a fixed fabrication process (MUMPS) and a fixed layout tool (L-Edit) are chosen. Thus our efforts are concentrated on reliable simulation of designs and eventual comparison with actual fabricated parts. The cantilever beam is chosen as an example of how extraction from a physical layout may be modeled and interfaced with various simulators.     

Social meaning of personal computers for managers and professionals: methodology and results

The social meaning of personal computers for 34 managers and professionals was measured using a situational approach. The results, in general, indicated a positive perception towards computers within the context of their work situations. The methodology was developed in an attempt to overcome some of the difficulties of traditional measures of attitudes. The advantages and the limitations of the method, as well as the process by which impressions are formed, are discussed.