Thermodynamic Measurements of Entropy-Stabilized Ultra-High Temperature Materials
Abstract
The pursuit of developing new Ultra-High Temperature Materials (UHTMs) is challenged by two significant scientific and technological hurdles being addressed in this proposal. The first hurdle is that previous efforts to increase the temperature range for new materials, driven solely by thermodynamic consideration of increasing enthalpy, have not led to any paradigm changes inmaterial performance. Recently, our efforts under an existing ONR-MURI entitled The Science of Entropy Stabilized Ultra-High Temperature Materials has resulted in the development of a broad class of new ceramics based on the concept of increasing the entropic state of a material that results in increased thermal stability with increasing temperature. Validation of the entropic kickrequires determination of several thermodynamic properties, specifically melting temperature and a lower temperature phase transition. With increasingly higher thermal properties of these materials, measurement of these critical validation parameters is beyond the capabilities of most laboratories. The second hurdle of this research is the technological challenge of accurately measuring a melting temperature above 4000C. Another major challenge in the materials development field is the extremely slow process of experimental validation of new bulk alloys; this challenge is also being addressed in this proposal.Our Twofold Scientific and Technological Objectives are (1) to develop the unique XRDUHTM characterization platform and completely validate its accuracy in measuring material thermodynamic properties such as very high solid-state phase transition temperature (Tc) and melting temperatures (Tm). These data will directly contribute to validation of the underlying science of five+-component entropy-stabilized UHTMs (ESUHTMs) and other advanced refractory alloys; and (2) to enhance the development of a unique high-throughput alloy development methodology that utilizes our previous 2016 DURIP-funded LAMS-UHTMs laseradditive facility for high-throughput alloy fabrication and with the current proposed XRD-UHTM system enabling the high-throughput XRD analysis of the sample array fabricated by the LAMSUHTM system. This secondary goal of the proposal will be a paradigm change in the field of experimental validation of new alloys of interest to the DoD community.The proposed XRD-UHTMs system will be used both for the specific, unique experiments outlined herein, but also housed and made available through our shared user facility, the NE-MRC, directly supporting a wide array of research projects in physical metallurgy and ceramics as well as additive manufacturing, and nanoengineering, disciplines that are critically important to theDoD mission. The close collaboration among two California public schools, University of California, San Diego and San Diego State University (a Title V Hispanic Serving Institution), is an additional strength.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 19, 2020
- Source ID
- N000142012872
Entities
People
- Kenneth Vecchio
Organizations
- Office of Naval Research
- United States Navy
- University of California, San Diego