Phase stability as a function of temperature in a refractory high-entropy alloy
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ARTICLE Phase stability as a function of temperature in a refractory highentropy alloy Vishal Sonib) and Bharat Gwalanib) Advanced Materials and Manufacturing Processes Institute, University of North Texas, Denton, Texas 76207, USA; and Department of Materials Science and Engineering, University of North Texas, Denton, Texas 76207, USA
Oleg N. Senkov Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433, USA; and Materials and Processes Division, UES Inc., Beavercreek, Ohio 45432, USA
Babu Viswanathan Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433, USA; and Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 4310, USA
Talukder Alam Advanced Materials and Manufacturing Processes Institute, University of North Texas, Denton, Texas 76207, USA; and Department of Materials Science and Engineering, University of North Texas, Denton, Texas 76207, USA
Daniel B. Miraclec) Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433, USA
Rajarshi Banerjeea) Advanced Materials and Manufacturing Processes Institute, University of North Texas, Denton, Texas 76207, USA; and Department of Materials Science and Engineering, University of North Texas, Denton, Texas 76207, USA (Received 6 April 2018; accepted 18 June 2018)
Refractory high-entropy alloys (RHEAs) have recently attracted much attention, primarily due to their mechanical properties at elevated temperatures. However, the equilibrium phase-stability of these alloy systems is not well established. The present investigation focuses on the phase stability of Al0.5NbTa0.8Ti1.5V0.2Zr RHEA at temperatures ranging from 600 to 1200 °C. The detailed phase characterization involves coupling of scanning electron microscopy, transmission electron microscopy, and atom probe tomography. The stable phases present at these temperatures are (i) 1200 °C—body-centered cubic (BCC) matrix with nano-B2 precipitates; (ii) 1000 °C and 800 °C—a BCC matrix phase with Al–Zr rich hexagonal closed packed intermetallic precipitates and, (iii) 600 °C—a BCC 1 B2 microstructure, comprising a continuous BCC matrix with discrete B2 precipitates. These results highlight the substantial changes in phase stability as a function of temperature in RHEAs, and high-entropy alloys in general, and also the importance of accounting for these changes especially while designing alloys for high temperature applications.
I. INTRODUCTION
High-entropy alloys (HEAs), also known as complex concentrated alloys, have generated a significant interest in the scientific community because of their unique microstructures and excellent mechanical properties.1–7 Recently, the development of a specific class of HEAs a)
Address all correspondence to this author. e-mail: [email protected] b) These authors contributed equally to this work. c) This author was an editor of this journal during the review and decision stage. For the JMR policy
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