| Abstract Scope |
High-throughput qualification and certification of many AM processes, materials, and components requires non-destructive imaging of crystal microstructures and textures. Polarized-light microscopy (PLM) has in- herent advantages over x-ray and electron microscopy for this purpose, although PLM must be optimized beyond traditional designs and algo- rithms in order to obtain quantitative information at high data rates. Herein several levels of quantitative texture–grain statistics, phase frac- tions, orientation-distribution functions, et al–are imaged and revealed in AM titanium, stainless steel, aluminum, and Inconel alloys over instant fields-of-view (FOV) approaching 2.3cm2, in under 45 minutes per sample on average (including processing time), and verified against electron microscopy where available. The laser PLM tolerates rougher surfaces—samples may be rotary-polished only—and common cubic al- loys are prepared with a brief (<1min) swab etch with a standard reagent. FOVs can be extended to arbitrarily large areas using a seamless stitch- ing routine that does not employ digital blending, demonstrated herein by a 2 square-inch Ti* c-axis image. Microscope design optimizations are mapped to requirements for high-throughput-imaging (FOV, speed, and surface tolerance) and compared to other PLMs, SRAS, and SEM imaging modes. |