A Comparison of Optical and SEM BSE Imaging Techniques for Quantifying Alpha-Beta Titanium Alloy Microstructures (Preprint)

Quantitative metallography is often used to confirm the proper processing of aerospace metallic materials. A microstructural feature of great importance for titanium alloys processed in the alpha-beta phase field is the volume fraction of primary alpha. Standard methods of measuring delineated featured within a microstructure have been established previous, such as ASTM E-112 for grain size and ASTM E-562 for fraction of secondary phase. An accepted standard, however, for imaging technique has not been established to determine the quantity of primary alpha in alpha-beta titanium alloys, and metallurgists in industry and academia often favor different imaging techniques. In the present work, the volume fraction of primary alpha was measured using both optical microscopy and SEM backscatter electron BSE techniques. A comparison of measurements from images from both techniques indicated that the volume fraction of primary alpha was essentially equivalent.