191. modeling and fabrication of a new class of high-entropy refractory interstitial carbides

Department: NanoEngineering
Research Institute Affiliation: Graduate Program in Materials Science and Engineering
Faculty Advisor(s): Kenneth S. Vecchio

Primary Student
Name: Tyler James Harrington
Email: tjharrin@ucsd.edu
Phone: 951-694-2581
Grad Year: 2019

Abstract
Bulk samples of four equiatomic, five-component, high-entropy refractory carbides were synthesized via a combination of high-energy ball milling, spark plasma sintering and hot pressing. The degree of microstructure homogeneity was improved by subsequent heat treatment at 2773K. In order to prepare an entropy-stabilized material, different configurations should have similar energies therefore increasing the number of thermodynamically accessible states. A partial occupation method was implemented within AFLOW to automate the generation and calculation of different configurations. The energy distributions were then used to construct a descriptor to predict the formation of these high-entropy materials. CALPHAD results were found to be in agreement with configuration energy range descriptor for each composition and three of these carbides exhibited broad, single-phase solubility across each system, making processing easier. Three of the complex carbide compositions, including (HfNbTaTiZr)C, (HfNbTaTiV)C, and (NbTaTiVW)C demonstrated virtually single-phase, solid-solution compounds and were sintered to greater than 95% theoretical density. The composition (HfMoTaWZr)C exhibited multiple phases as was predicted by both CALPHAD and the configuration energy range descriptor.

Industry Application Area(s)
Aerospace, Defense, Security | Energy/Clean technology | Materials

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