Paper Title:

High-Entropy Alloys – A New Era of Exploitation

Periodical Materials Science Forum (Volume 560)
Main Theme Advanced Structural Materials III
Edited by H. Balmori-Ramirez, J.G. Cabañas-Moreno, H.A. Calderon-Benavides, K. Ishizaki and A. Salinas-Rodriguez
Pages 1-9
DOI 10.4028/www.scientific.net/MSF.560.1
Citation Jien Wei Yeh et al., 2007, Materials Science Forum, 560, 1
Online since November 2007
Authors Jien Wei Yeh, Yu Liang Chen, Su Jien Lin, Swe Kai Chen
Keywords Amorphous Phase, High Entropy Alloy, High-Entropy Effect, Nanostructure
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A high-entropy alloy (HEA) has been defined by us to have at least five principal elements, each of which has an atomic concentration between 5% and 35%. In the exploration on this new alloy field, we find that HEAs are quite simple to analyze and control, and they might be processed as traditional alloys. There exist many opportunities to create novel alloys, better than traditional ones in a wide range of applications. In this paper, we review the basic microstructural features of HEAs and discuss the mechanisms of formation. Instead of multiple intermetallic phases, the HEAs tend to form simple solid solution phases mainly of cubic crystal structure, especially at elevated temperatures. This tendency is explained by the high entropy effect based on the simple relation: (Gmix = (Hmix – T(Smix, and the second law of thermodynamics. Moreover, nanostructures and amorphous phases are easily formed in HEAs. This tendency is explained by kinetics theory as due to slow atomic diffusion.

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