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

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.
Authors:
 [1] ;  [2] ;  [1] ;  [3]
  1. ORNL
  2. Argonne National Laboratory (ANL)
  3. AdaptaMat, Finland
Publication Date:
OSTI Identifier:
1154790
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: 35th Risoe international meeting, Roskilde, Denmark, 20140901, 20140905
Research Org:
Oak Ridge National Laboratory (ORNL)
Sponsoring Org:
ORNL LDRD Seed-Money
Country of Publication:
United States
Language:
English
Subject:
shape memory alloys; boundaries; strain; microdiffraction