Effects of processing on the mechanical properties and oxidation behavior of Al{sub 2}Ti

Al{sub 2}Ti is a promising material for use in elevated temperature structural applications. It has a lower density than Ti{sub 3}Al and TiAl. The authors have previously shown that the compressive yield strength of Al{sub 2}Ti is higher than that of similarly processed TiAl and Al{sub 3}Ti between room temperature and 900 C. In this study, two additional processing methods were utilized to produce the material: uniaxial hot pressing of rapidly solidified powder and hot forging of cast ingots. Effects of hot forging or annealing of as-cast Al{sub 2}Ti on the microhardness and load for crack initiation were studied. The microhardness and crack initiation load were also used to compare powder processed material consolidated either by hot pressing or hot isostatic pressing. The oxidation behavior of as-cast, cast and hot isostatically pressed (cast and hip`ed), and powder processed and hip`ed (PP) Al{sub 2}Ti was also investigated. The oxidation tests were performed in air at 815 C and 982 C for 100 hr. PP Al{sub 2}Ti exhibited the lowest weight gain and as-cast exhibited the highest. Al{sub 2}Ti shows superior oxidation resistance compared to Ti{sub 3}Al- and TiAl- based alloys tested under similar conditions and shows comparable oxidation resistance to Al{submore » 3}Ti at 800 C. SEM/EDS was used to study the morphological development of the oxide scale and to identify the chemical constituents present in the various layers of the scale.« less