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Title: Indentation-induced localized deformation and elastic strain partitioning in composites at submicron length scale

Journal Article · · Acta Mater.

Three-dimensional spatially resolved strains were mapped in a model NiAl/Mo composite after nanoindentation. The depth-dependent strain distributed in the two phases and partitioned across the composite interfaces is directly measured at submicron length scale using X-ray microdiffraction and compared with a detailed micromechanical stress analysis. It is shown that indentation-induced deformation in the composite material is distinct from deformation expected in a single-phase material. This difference arises in part from residual thermal strains in both phases of the composite in the as-grown state. Interplay between residual thermal strains and external mechanical strain results in a complex distribution of dilatational strain in the Mo fibers and NiAl matrix and is distinct in different locations within the indented area. Reversal of the strain sign (e.g., alternating tensile/compressive/tensile strain distribution) is observed in the NiAl matrix. Bending of the Mo fibers during indentation creates relatively large 1.5{sup o} misorientations between the different fibers and NiAl matrix. Compressive strain along the <0 0 1> direction reached -0.017 in the Mo fibers and -0.007 in the NiAl matrix.

Research Organization:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Organization:
USDOE
OSTI ID:
1002812
Journal Information:
Acta Mater., Vol. 58, Issue (20) ; 12, 2010; ISSN 1359-6454
Country of Publication:
United States
Language:
ENGLISH