Abstract
The microstructural-controlling of uni-directionally solidified Ni-Al-Mo in-situ composites has been conducted by changing growth rates and by the addition of rhenium (Re) or iridium (Ir). Oxidation resistance at 1000°C in air and high temperature strength at 800°C of these in-situ composites have also been examined and have been compared with those of conventional Ni-base superalloys, such as MAR-M247 and IN-100. The morphology of strengthening phase, that is Mo phase, changed from fiber-like shape to plate-like shape with increasing the growth rate. A superior oxidation resistance evaluated for 30h was observed for Ni-Al-Mo-Ir in-situ composites. On the other hand, high strength and large fracture strain were obtained for Ni-Al-Mo-Re in-situ composites. Experimental results showed that these composites possessed excellent high temperature properties, which was better than or comparable with those of Ni-base superalloys.
