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Title
Japanese: 
English:Effect of Dislocation Sources on Slip in Fe2Nb Laves Phase with Ni in Solution 
Author
Japanese: 高田 尚記, Gassemi-Armaki Hassan, 寺田 芳弘, 竹山 雅夫, Shavan Kumar.  
English: Naoki Takata, Hassan Gassemi-Armaki, Yoshihiro Terada, Masao Takeyama, Kumar Shavan.  
Language English 
Journal/Book name
Japanese: 
English:2012 MRS FALL MEETING PROGRAM & EXHIBIT GUIDE 
Volume, Number, Page         p. 416
Published date Nov. 25, 2012 
Publisher
Japanese: 
English:Materials Reseatch Society 
Conference name
Japanese: 
English:2012 MRS FALL MEETING 
Conference site
Japanese: 
English:Boston, MA 
Official URL http://www.mrs.org/f12-program-jj/
 
Abstract The mechanical properties of the Fe2Nb Laves phase (C14 structure) in equilibrium with γ-Fe (fcc) changes substantially depending on the type of ternary solute atoms. Ni atoms replacing Fe atoms in Fe2 sublattice sites introduces basal planar faults and significantly softens the Fe-rich Laves phase; this suggests that Ni in solution may enhance the plastic deformability of the Laves phase. To demonstrate this possibility, we have examined mechanical properties of the Laves phases by uniaxial compression of ~2 μm diameter micropillars produced by focused ion beam milling from a Fe-Nb-Ni ternary alloy consisting of a two-phase microstructure of the Laves phase and γ-Fe. The Laves phase micropillars exhibit high strength of about 6 GPa (~G/30) approaching the theoretical shear strength of the material, followed by a burst of plastic strain and shear failure on the basal plane. If dislocation sources in the form of dislocation loops on a non-basal plane are introduced into the Laves phase micropillars by nanoindentation prior to compression, yielding occurs at a significantly lower stress level of about 3 GPa and plastic deformation by slip proceeds on a pyramidal plane close to (-1-122). Furthermore, if regenerative dislocation sources for basal slip are present in the micropillar, the Laves phase can be continuously plastically deformed in a stable manner to at least 5% strain with plastic deformation commencing at a significantly lower stress of 800 MPa. The corresponding critical resolve shear stress (CRSS) for moving these basal dislocations is ~310 MPa. We thus demonstrate an approach to examine/obtain fundamental plasticity parameters in traditionally brittle materials. Part of this study was carried under the research activities of “Advanced Low Carbon Technology Research and Development Program” (ALCA) in JST (Japan Science and Technology Agency).

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