Lightweight High Temperature Beta Gamma Alloy/Process Development for Disk and Blade Applications, Phase I

The primary material and manufacturing limitations of gamma TiAl alloys include processing difficulties, requiring costly non-conventional processing requirements, and large lamellar grains, which reduces damage tolerance. We have developed a new class of TiAl-based alloys, called beta gamma, which would remove such barriers. Unlike existing gamma alloys, beta gamma alloys are designed such that the ductile â phase is adequate at elevated temperatures (for processing) but negligible at the anticipated use temperatures (for performance). The alloys also feature significant grain refinement and compositional homogeneity. This program is aimed to utilize such beneficial beta-phase distribution and microstructure features observed in small (0.7kg) samples into forged disks from medium size (25kg) ingots. The process-ability will be validated by employing a conventional forging process, and refined lamellar microstructures will be generated through usual alpha treatments. The significance of this innovation is that beta gamma alloy disks can not only be produced by conventional forging, but also show improvements in RT strength and ductility and may retain other attributes (density, creep and oxidation) of conventional gamma alloys. More »