4D STUDY OF STRAIN GRADIENTS EVOLUTION IN TWINNED NiMnGa SINGLE CRYSTALS UNDER MAGNETIC FIELD

Conference · Tue Dec 31 23:00:00 EST 2013

OSTI ID:1154790

Barabash, Rozaliya ^[1]; Xu, Ruqing ^[2]; Barabash, Oleg M ^[1]; Sozinov, Alexei ^[3]

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1. ORNL
2. Argonne National Laboratory (ANL)
3. AdaptaMat, Finland

Time-resolved 3D X-ray microscopy with a submicron beam size was used to follow the evolution of strains in off-stoichiometric NiMnGa twinned crystals near type I (hard) twin boundary under magnetic field. Laminate A/B microstructure was revealed near the twin boundaries in A variant. Large strain gradients are observed in the C variant in the immediate vicinity of the type I twin boundary: the lattice is under large tensile strains ~0.4% along the c- axes within first micron. Distinct a and b lattice parameter evolution with temperature and magnetic field is demonstrated. In an applied magnetic field the strain field was observed at larger distances from the twin boundary and becomes more complex. Stochastic twin boundary motion was observed after the magnetic field reaches a certain critical value.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: ORNL LDRD Seed-Money
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1154790
• Country of Publication: United States
• Language: English

Related Subjects

boundaries
microdiffraction
shape memory alloys
strain