Constant plane shift model: Structure analysis of martensitic phases in Ni50Mn27Ga22Fe1 beyond non-modulated building blocks
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Date
2023-05-30
Authors
Vinogradova, Mariia
Sozinov, Alexei
Straka, Ladislav
Veřtát, Petr
Heczko, Oleg
Zelený, Martin
Chulist, Robert
Lähderanta, Erkki
Ullakko, Kari
ORCID
0000-0001-6715-4088Advisor
Referee
Mark
Journal Title
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Volume Title
Publisher
Elsevier
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Abstract
Martensites of Ni-Mn-Ga-based alloys consist of hierarchical twinning domains spanning from micro-to nanoscale. This affects the diffraction pattern and thus can decrease the accuracy of the determination of the crystal structure. We propose a method to obtain different martensitic phases in Ni-Mn-Ga-Fe alloy with simplified variant microstructures and domain sizes of more than 2 micrometers. The use of simplified variant microstructures allows the influence of nanometer-scale domains on diffraction line position to be circumvented and enabls the comparison of the lattice parameters of non-modulated (NM), five-layered modulated (10M), and seven-layered (14M) phases in the same temperature range due to the large hysteresis of the intermartensitic transformations. It is found that the short crystallo-graphic axes in NM, 14M, and 10M martensites at the same temperature have different lengths. As a result, equilibrium NM structure building blocks cannot be used to build the crystal structures of 14M and 10M martensites. Instead, we introduce a constant plane shift model with identical shift values of the nearest planes (110) along [(1) over bar 10] or [1 (1) over bar0] as a replacement for the tetragonal building blocks model. The work demonstrates that plane shift values differ dramatically between mar-tensites, which agrees with ab initio calculations. The application of the constant plane shift and hard sphere models in modulated lattices for atomic-level twinning considerations is discussed.
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Citation
ACTA MATERIALIA. 2023, vol. 255, issue 1, p. 1-11.
https://www.sciencedirect.com/science/article/pii/S1359645423003737
https://www.sciencedirect.com/science/article/pii/S1359645423003737
Document type
Peer-reviewed
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Published version
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en