Laves phases: a review of their functional and structural applications and an improved fundamental understanding of stab
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Laves phases: a review of their functional and structural applications and an improved fundamental understanding of stability and properties Frank Stein1,* 1 2
and Andreas Leineweber2
Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Düsseldorf, Germany Institute of Materials Science, TU Bergakademie Freiberg, Gustav-Zeuner-Str. 5, 09599 Freiberg, Germany
Received: 28 August 2020
ABSTRACT
Accepted: 25 October 2020
Laves phases with their comparably simple crystal structure are very common intermetallic phases and can be formed from element combinations all over the periodic table resulting in a huge number of known examples. Even though this type of phases is known for almost 100 years, and although a lot of information on stability, structure, and properties has accumulated especially during the last about 20 years, systematic evaluation and rationalization of this information in particular as a function of the involved elements is often lacking. It is one of the two main goals of this review to summarize the knowledge for some selected respective topics with a certain focus on non-stoichiometric, i.e., non-ideal Laves phases. The second, central goal of the review is to give a systematic overview about the role of Laves phases in all kinds of materials for functional and structural applications. There is a surprisingly broad range of successful utilization of Laves phases in functional applications comprising Laves phases as hydrogen storage material (Hydraloy), as magneto-mechanical sensors and actuators (Terfenol), or for wear- and corrosion-resistant coatings in corrosive atmospheres and at high temperatures (Tribaloy), to name but a few. Regarding structural applications, there is a renewed interest in using Laves phases for creep-strengthening of high-temperature steels and new respective alloy design concepts were developed and successfully tested. Apart from steels, Laves phases also occur in various other kinds of structural materials sometimes effectively improving properties, but often also acting in a detrimental way.
The Author(s) 2020
Handling Editor: P. Nash.
Address correspondence to E-mail: [email protected]
https://doi.org/10.1007/s10853-020-05509-2
J Mater Sci
Contents 1 2
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Introduction .......................................................................... 2 Some remarks about the Laves phase structures and their particular role and uniqueness among intermetallic phases .................................................................................... 4 Fundamental aspects........................................................... 7 3.1 Stability and site preference...................................... 7 3.2 Point defects—the binary case.................................. 10 3.2.1 Constitutional point defects...................... 10 3.2.2 Thermal point defects................................ 13 3.3 Polytypism ................................................................... 15 3.4 CALPHAD modeling ............................................
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