High Temperature Strength of Structure-Controlled Ni-Al-Mo In-Situ Composites
Hitoshi TAKAGI, Koji TAKAHASHI and Sumio FUJIMURA
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 in air and high temperature strength at 800 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. Key Words:In-situ composites, Ni-Al-Mo alloy, High temperature strength, Ni-base superalloy, Growth rate, Re, Ir