No Cover Image

Journal article 447 views 85 downloads

The Effect of Scandium Ternary Intergrain Precipitates in Al-Containing High-Entropy Alloys / Sephira Riva, Shahin Mehraban, Nicholas Lavery, Stefan Schwarzmüller, Oliver Oeckler, Stephen Brown, Kirill Yusenko, Steve Brown

Entropy, Volume: 20, Issue: 7, Start page: 488

Swansea University Authors: Nicholas Lavery, Steve Brown

Check full text

DOI (Published version): 10.3390/e20070488

Abstract

We investigate the effect of alloying with scandium on microstructure, high-temperature phase stability, electron transport, and mechanical properties of the Al2CoCrFeNi, Al0.5CoCrCuFeNi, and AlCoCrCu0.5FeNi high-entropy alloys. Out of the three model alloys, Al2CoCrFeNi adopts a disordered CsCl str...

Full description

Published in: Entropy
ISSN: 1099-4300
Published: 2018
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa40823
Tags: Add Tag
No Tags, Be the first to tag this record!
Abstract: We investigate the effect of alloying with scandium on microstructure, high-temperature phase stability, electron transport, and mechanical properties of the Al2CoCrFeNi, Al0.5CoCrCuFeNi, and AlCoCrCu0.5FeNi high-entropy alloys. Out of the three model alloys, Al2CoCrFeNi adopts a disordered CsCl structure type. Both of the six-component alloys contain a mixture of body-centered cubic (bcc) and face centered cubic (fcc) phases. The comparison between in situ high-temperature powder diffraction data and ex situ data from heat-treated samples highlights the presence of a reversible bcc to fcc transition. The precipitation of a MgZn2-type intermetallic phase along grain boundaries following scandium addition affects all systems differently, but especially enhances the properties of Al2CoCrFeNi. It causes grain refinement; hardness and electrical conductivity increases (up to 20% and 14% respectively) and affects the CsCl-type → fcc equilibrium by moving the transformation to sensibly higher temperatures. The maximum dimensionless thermoelectric figure of merit (ZT) of 0.014 is reached for Al2CoCrFeNi alloyed with 0.3 wt.% Sc at 650 °C.
Keywords: high-entropy alloys; in situ X-ray diffraction; grain refinement; thermoelectric properties; scandium effect
College: College of Engineering
Issue: 7
Start Page: 488