Morphology and Structure of Compacted Coated Powders Studied by SEM and TEM

Abstract

The interest in titanium based intermetallics, such as Ti-Al alloys, for high temperatures applications has been increased in recent years mainly due to their high plastic deformation resistance, chemistry stability (oxidation and corrosion resistance) and creep and fatigue resistance at high temperatures. However, the industrial application of Ti-Al intermetallics is very limited so far, due to the lack of ductility and fracture toughness at room temperature with associated processing difficulties. To overcome this problem and to improve mechanical properties of Ti-Al intermetallics, a powder mixture with atomic composition of Ti₅₂Al₄₈ was synthesized by mechanical alloying (MA) and subsequently coated with a ductile element (aluminium), by d.c. magnetron sputtering. Later, in order to obtain a compacted material, as final step, the coated MA'ed powders were submitted to hot isostatic pressing (HIP), giving rise to a bulk material. The aim of the current work is to understand the influence of coating layer in mechanical alloyed (MA'ed) powders and the influence in bulk material properties.