Glassy Phonon Heralds a Strain Glass State in a Shape Memory Alloy

Shape memory strain glasses are frustrated ferroelastic materials with glasslike slow relaxation and nanodomains. It is possible to change a NiCoMnIn Heusler alloy from a martensitically transforming alloy to a nontransforming strain glass by annealing, but minimal differences are evident in the sho...

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Bibliographic Details
Published in:Physical review letters 2018-06, Vol.120 (24), p.245701-245701, Article 245701
Main Authors: Stonaha, P J, Karaman, I, Arroyave, R, Salas, D, Bruno, N M, Wang, Y, Chisholm, M F, Chi, S, Abernathy, D L, Chumlyakov, Y I, Manley, M E
Format: Article
Language:English
Subjects:
Annealing
Damping
Displacements (lattice)
Disruption
Ferroelastic materials
First principles
Glass
Heusler alloys
Long range order
Martensitic transformations
Neutron scattering
Shape memory alloys
Stability
Transition temperature
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Summary:Shape memory strain glasses are frustrated ferroelastic materials with glasslike slow relaxation and nanodomains. It is possible to change a NiCoMnIn Heusler alloy from a martensitically transforming alloy to a nontransforming strain glass by annealing, but minimal differences are evident in the short- or long-range order above the transition temperature-although there is a structural relaxation and a 0.18% lattice expansion in the annealed sample. Using neutron scattering we find glasslike phonon damping in the strain glass but not the transforming alloy at temperatures well above the transition. Damping occurs in the mode with displacements matching the martensitic transformation. With support from first-principles calculations, we argue that the strain glass originates not with transformation strain pinning but with a disruption of the underlying electronic instability when disorder resonance states cross the Fermi level.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.120.245701