XRD Investigations of the Phosphorus Effect on the Oxidation of TiAl Alloys by High-Resolution Methods

摘要: Recently it has been found that very small amounts (a few 100 ppm) of Padded to γ -titanium aluminide can significantly alter the oxidationbehavior between 973 and 1273 K. The mechanism responsible for this changeis, however, still not clear. In present study, phosphorus wasincorporated into surface TiAl (containing 50 at.% Al) by ionimplantation oxidation tests were carried out at 1173 K inair. Improvement resistance is only temporary up hr forphosphorus-implanted TiAl. After hr, rate increases andbreakaway follows. XRD EPMA showed breakawayoxidation connected with massive nitride formation. Two different modelsare proposed which explain effect additions on theoxidation kinetics during protective stage within first100 hr. breakaway be explained penetration air themetal–oxide interface zone because microcrack formation in theoxide scale, was experimentally proved acoustic-emission analysis.