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The TACTILS outreach program Marc De Graef, Carnegie-Mellon University, DMR 1005330

In-situ Lorentz magnetization study on a Fe-Pd-Co martensitic alloy Marc De Graef, Carnegie-Mellon University, DMR 1005330.

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The TACTILS outreach program Marc De Graef, Carnegie-Mellon University, DMR 1005330

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  1. In-situ Lorentz magnetization study on a Fe-Pd-Co martensitic alloyMarc De Graef, Carnegie-Mellon University, DMR 1005330 The ability of magnetic domain walls to move around in a ferromagnetic shape memory alloy is crucial to the use of such materials in actuator applications. We have used in-situ Lorentz microscopy to study the motion of domain walls as a function of applied field in Fe-Pd-Co martensitic alloys. We found that the motion was strongly influenced by the presence of twin boundaries; free-standing domain walls move at fields as low as 15 Oe, whereas an order of magnitude stronger fields are required when the walls are pinned on twin boundaries. Understanding these inter-actions may lead to improved actuator materials by modifying the composition and processing conditions to reduce the pinning field strength. A.Budruk, C. Phatak, A.K. Petford-Long & M. DeGraef, Acta Materialia, 2011 (in press) Lorentz images from a twinned region as a function of applied field. The color indicates the direction of the local magnetization. The yellow domains reduce in size and change shape as the field increases.

  2. The TACTILS outreach programMarc De Graef, Carnegie-Mellon University, DMR 1005330 TACTILS stands for Teaching Advanced Characterization Tools In Local Schools. It is an outreach program with as ultimate goal to make it possible for high school science teachers to use scanning electron microscopes remotely from their class room as part of their high school science curricula. In July 2011, we held a small 8-day workshop at CMU, attended by four science teachers from local high schools; they were taught how to use two different desktop microscopes, they made a variety of samples, and initiated the creation of lesson plans that will be piloted during the Fall of 2011. The workshop was a success, and will lead to a larger workshop during the Summer of 2012. The long term goal is to make about a dozen instruments available for remote high school use. The workshop was carried out with NSF support (this program as well as RET support), as well as in-kind support from the ASPEX Corporation, and the CMU Leonard Gelfand Center for Service Learning and Outreach. Example desktop SEM images taken by high school science teachers in preparation of lesson plans for the Fall 2011 semester. Top row: micro-meteorites taken from a rain gutter (low and high mag; meteorites are the spherical particles); bottom left: glass droplet re-solidified on a tungsten filament wire; bottom right: a mite collected from a pine cone.

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