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| Automated reflection Laue and serial sectioning characterization of magnetic and martensitic materials [NSF] | |
| With AFOSR-DURIP support we have recently acquired an automated metallographic polishing unit, known as Robomet.3D. The original Robomet-3D instrument (R3D) was designed and built at Wright Patterson Air Foce Base by Dr. Jonathan Spowart and his colleagues (working as UES contractors). Funding for the prototype was provided by an AFOSR lab task, entitled ``Metallic materials with high structural efficiency.'' The design involved combining various off-the-shelf components with custom integration and engineering, to obtain an efficient, high-throughput serial sectioning platform. R3D uses polishing (diamond lapping) rather than milling to obtain section thicknesses of 0.2 to 10 microns, and can achieve (depending on the material being sectioned) about 20 sections per hour; each section is imaged on an optical microscope with automated x-y stage, resulting in a potentially large field of view. The typical analyzed volume can amount to several cubic millimeters. Samples analyzed with the WPAFB instrument include discontinuously reinforced aluminum; sintered iron-copper; structural carbon foam; and freckle defects in Ni-based super alloys.
The central component of the instrument is a Rixan RV-3S-S11 robot arm, capable of lifting a 3 kg weight, and with a 642 mm reach. The robot arm has 6 degrees of freedom and is fully programmable. The robot is located near the center of a large granite table onto which the other system components are mounted. The main components in the standard setup are:
The robot transports the sample mount between the various components, and all components work autonomously, controlled by Visual Basic routines on a central computer. |
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The object on the right, mounted on long square legs, is a new Laue diffraction unit consisting of an x-ray tube (white cylinder), a dual CCD detector (black box), and a vertically mounted high-precision x-y stage. The robot arm can bring the sample to the x-y stage which then positions it in front of the x-ray beam. The system is currently (Fall 2009) under construction. It is our goal to integrate the Laue unit with the rest of R3D, so that we can obtain diffraction patterns from individual grains in the sample. The integration process consists of two phases: first, we will determine a method to accurately position a single grain, identified by means of optical microscopy and image analysis, in front of the 10 micron x-ray beam. Once this works, then we will need to create a "smart-scan" approach, in which we make sure that each grain in the sample is scanned only once (each scan takes 20-30 seconds, so we can not possibly hope to do a detailed grid scan for each slice). Once the system works fully, we will describe the setup in a paper to be published in a journal to-be-determined... |
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| Recent Publications:
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