ECI Digital Archives

Title

Fabrication of high-entropy nitrides and carbonitrides

Authors

Olivia F. Dippo, University of California at San Diego, USAFollow
Tyler J. Harrington, University of California at San Diego, USA
Eduardo Marin, University of California at San Diego, USA
William. M. Mellor, University of California at San Diego, USA
Matthew C. Quinn, University of California at San Diego, USA
Kenneth S. Vecchio, University of California at San Diego, USA
Cormac Toher, Duke University
Stefano Curtarolo, Duke University
Pranab Sarker, Duke University

Conference Dates

September 17-20, 2017

Abstract

In high-entropy alloys, the use of multiple principle alloying elements is known to entropically stabilize the material. Refractory nitrides and carbides of transition metals are widely known for their ultra high-temperature stability and their high hardness, properties that make them valuable materials for extreme environments, such as coating the exterior of hypersonic flight vehicles and the interior of nuclear reactors. By creating entropy-stabilized complex solid solutions of nitrides and carbides, one can take advantage of the inherent favorable properties of these materials, as well as increased thermal stability and solid solution strengthening. Five-metal systems are chosen using first-principles calculations to describe the energetic distribution of possible atomic configurations, in order to identify systems that are likely to form an entropy-stabilized solid solution. Bulk samples of equiatomic, hexanery (5-metal), high-entropy refractory nitrides and carbonitrides were then fabricated to demonstrate this concept, by using a combination of high-energy ball milling, spark plasma sintering, and hot pressing. The uniformity of the microstructures is characterized, and single-phase solid solutions are achieved, thus demonstrating the ability to entropically stabilize multi-component random mixtures of refractory carbides and nitrides.

This work is supported by the U.S. Office of Naval Research MURI program (Grant No. N00014-15- 1-2863)

Recommended Citation

Olivia F. Dippo, Tyler J. Harrington, Eduardo Marin, William. M. Mellor, Matthew C. Quinn, Kenneth S. Vecchio, Cormac Toher, Stefano Curtarolo, and Pranab Sarker, "Fabrication of high-entropy nitrides and carbonitrides" in "Ultra-High Temperature Ceramics: Materials for Extreme Environment Applications IV", Jon Binner, The University of Birmingham, Edgbaston, United Kingdom Bill Lee, Imperial College, London, United Kingdom Eds, ECI Symposium Series, (2017). https://dc.engconfintl.org/uhtc_iv/10