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An in situ neutron diffraction study of anomalous superelasticity in a strain glass Ni 43 Fe 18 Ga 27 Co 12 alloy
Author(s) -
Zhang Q. H.,
Zhai Z.,
Nie Z. H.,
Harjo S.,
Cong D. Y.,
Wang M. G.,
Li J.,
Wang Y. D.
Publication year - 2015
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s1600576715011334
Subject(s) - pseudoelasticity , materials science , diffusionless transformation , neutron diffraction , deformation (meteorology) , shape memory alloy , martensite , alloy , condensed matter physics , crystallography , metallurgy , composite material , crystal structure , microstructure , chemistry , physics
Superelastic behavior is traditionally related to the martensitic transition with a collective transformation scenario in some shape memory alloys. A kind of quasi‐linear superelasticity accompanied by a finite avalanche or confined martensitic transformation was recently found in some alloy systems with strain glass state. Here, an in situ neutron diffraction technique was used to study the deformation behavior in an Ni 43 Fe 18 Ga 27 Co 12 alloy with strain glass state in order to reveal the new intrinsic physical nature of the quasi‐linear superelasticity. A significant modulus softening prior to the stress‐induced martensitic transformation was observed during compression in the studied alloy, which is similar to the characteristics exhibited in the tweed precursor phenomena prior to temperature‐induced martensitic transformation. Moreover, the diffraction peak broadening was further shown during the elastic stage of deformation for both single‐crystal and polycrystalline samples, which mainly stems from the short‐range fluctuation in the strain field inside each grain based on Williamson–Hall analysis. The authors believe that there exists a spatial heterogeneity in the modulus of the confined martensitic transformation alloy.