AN AUGER INVESTIGATION OF THE FRACTURE-BEHAVIOR OF PST TIAL ALLOYS

Samples of two polysynthetically twinned (PST) TiAl alloys (Ti-49 at% Al and Ti-49 at% Al-0.6 at%Cr) were fractured under different environm ental conditions at room temperature, and the fracture surfaces were a nalyzed using scanning Auger and scanning electron microscopy. These t echniques were employed to determine the fracture mode and the chemica l composition of the fracture surfaces of the TiAl alloys. Our study c learly indicates that all of the fracture surfaces exposed by bend tes ting were at, except when fractures occurred across the lamellae. No c hromium enrichment was observed on any of the exposed surfaces. From t hese observations, it was concluded that the fracture mode for these m aterials is cleavage through the alpha(2)-phase. (C) 1997 Elsevier Sci ence Limited.