Influence of Group IV and V Alloying Elements on the Microstructure Engineering and Deformation Behavior in Tantalum Carbides.

摘要

Tantalum carbides comprise a class of high and ultrahigh melting temperature materials with tremendous thermo-mechanical property potential. This program provided a fundamental series of studies to address how group IVB and VB metal carbide alloying brings about microstructural engineering with subsequent changes in thermo-mechanical behavior. The program employed a combined computational and experimental approach coupled through advanced analytical electron microscopy characterization to address this gap. Major findings include determination of an intrinsic stacking fault on the {111} planes in TaC that circumvents slip on {110}, which is the dominant slip plane in HfC; the competition of vacancy ordered and fault-forming phases with metal-enrichment in Ta-C; the formation of vacancy ordered phase domains which are hypothesized to contribute to an anomalous rise in hardness for the group VB carbides absent in group IVB carbides; and finally construction of a non-contact Lorentz force thermo-mechanically loading apparatus for testing these carbides above 3000 deg. C.