Phase stability of the intermetallic L2 1 Heusler alloys of A 2 (Hf 1-x Zr x)Al (where A=Pd and Pt) for an Nb-based high-temperature materials design

Miyoung Kim, A. J. Freeman, Sungtae Kim, J. H. Perepezko, G. B. Olson

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Abstract

First principles phase stability calculations are used to predict the lattice mismatches between Nb and the A2 (Hf1-x Zrx) Al L 21 Heusler phases and the L 21 phase formation energies, where A=Pd andor Pt, and x=0, 0.25, 0.75 and 1. The calculated L 21 phase mixing energy demonstrates that the Hf-Zr solution phases in the form of A2 (Hf1-x Zrx) Al (x≠0 and 1) are energetically favored, although the Zr-rich alloys exhibit a smaller lattice mismatch than the Hf-rich alloys. The introduction of Pt reduces the lattice mismatch, and forms the energetically favorable (PtPd)XAl Heusler phase, where X=Hf and Zr. A number of critical diffusion couple experiments confirm the phase stability predictions and establish new microstructural design parameters.

Original languageEnglish
Article number261908
Pages (from-to)1-3
Number of pages3
JournalApplied Physics Letters
Volume87
Issue number26
DOIs
Publication statusPublished - Dec 1 2005

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ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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