Research with in-situ Composites Aligned with Eutectoid and Eutectic Transformations.

Directionally aligned eutectoids are of potential interest for high temperature turbine applications. The Hf-HfCr2 eutectoid was selected from several systems, to explore the potential of using solid-solid transformation to yield a suitable, aligned microstructure. A series of Ni-TaC alloys and a NiCr-Ni3Al-Ni3Nb alloy have been examined in oxidation. Numerous effects dependent on microstructures, chemistry, and oxidation temperature were observed. Chemical vapor deposition CVD techniques were used to deposit simple and complex layers of the elements Ni, Cr, and Al required for high temperature, oxidation resistant coatings. This work demonstrated the feasibility of depositing sequential layers.