SPICES: Spinodal-hardened high-entropy ceramics
Abstract
SPICES: Spinodal-hardened high-entropy ceramics is built on coherent spinodaldecomposition of high-entropy transition-metal ceramics. This unique pathway combines covalent bonding optimization, an energy landscape impervious to dislocation motion, a highly interlocked coherent nanostructure to optimize hardness across scales by multiple mechanisms, and a freedom to optimize chemical resistanc high-throughput thermodynamics, advances in Machine Learning capabilities,detailed theoretical insights, leading expertise in materials synthesis, and access to a wide range of characterization tools. Hardness is the measure of a material s resistance to permanent deformation with applied stress. It is a qualitative quantity that also depends on the measurement method andinterpretation. A material is super-hard when its Vickers hardness exceeds 40 GPa, and ultra-hard when it is between cubic-BN and diamond. Our team has already prepared preliminary high-entropy super-hard diborides: this proposal will translate these into the ultra-hard realm using coherent spinodal decomposition. Given the freedom of SPICES, we will build tools and expertise to understand and control the many mechanisms of hardness andchemical resistance: 1) chemical composition, which determines covalent character and thus the incompressible mechanical response at low loads; 2) inhomogeneity, as diversity of elemental radii, masses, valences and electronegativities generates a rugged energy landscape resisting dislocation motion and slip; 3) entropy, working as a deformation reservoir" for elastic energy by dynamically rearranging species, and hindering/postponing the onset of stress induced phase transitions (the problem of many ordered diborides); 4) enthalpy, as its balance with congurational entropy enables engineering a continuum of nanostructures spanning from homogeneous crystals to coherent spinodally decomposed composites (the righernal strains that arrest plastic deformation, without producing the weak links typical of incoherent interfaces); and 5) inertness,/carbide/nitrides, due to their resistance to chemical reactions when in contact with iron, steel and other alloys at elevated tempeations: i. understanding what makes an ideal material hard; ii. understanding the interplay between properties and morphologies for hardness; iii. creating a rapid protocol | HARD-FLOW | a combination of ab-initio, Machine Learning, synthesis and characterization to describe hardness, thermodynamics, and chemical stability; iv. extracting interpretable descriptors for hardness, to help autonomous guided ICME-basedmaterials development; and v. synthesizing and characterizing the super-/ultra-hard materials. Our endeavor ushers in a new era of materials design: the pivotal principle is an accelerated high-throughput search for easy-to-synthesize disordered ceramics with ad hoc mechanical properties, validated by our extensive materials algorithms and databases. The theoretical andMachine Learning predictions are closely coupled with accelerated experimental verification, which in turn provides rapid feedback for further theoretical investigations. Our mission is to establish a comprehensive platform bringing together advanced thermodynamics, electronic structure methods, new approaches to data-driven hardness-model building, and scalable synthesis strategies. The end product of our research will be an infrastructure to serve theDoD s diverse materials needs. Our discovery engine will be open to the materials community at large for a variety of design issues beyond the specic application of chemical resistant super-/ultra-hard materials.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 09, 2021
- Source ID
- N000142112515
Entities
People
- Stefano Curtarolo
Organizations
- Duke University
- Office of Naval Research
- United States Navy