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

• Published in: Acta materialia Vol. 58; no. 20; pp. 6784 - 6789
• Main Authors: Barabash, R.I., Bei, H., Gao, Y.F., Ice, G.E.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.12.2010; Elsevier
• Subjects: Aluminides; Applied sciences; BENDING; COMPOSITE MATERIALS; Composites; DEFORMATION; DISTRIBUTION; Exact sciences and technology; FIBERS; Intermetallic compounds; Intermetallics; MATERIALS SCIENCE; Metals. Metallurgy; Micro-/nanoindentation; Micromechanics; Nickel aluminides; Nickel base alloys; Nickel compounds; Strain; STRAINS; STRESS ANALYSIS; X-ray synchrotron radiation; Micromechanics; Micro-/nanoindentation; Composites; Deformation; X-ray synchrotron radiation; Indentation; Composite material; Synchrotron radiation
• ISSN: 1359-6454; 1873-2453
• DOI: 10.1016/j.actamat.2010.09.004

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° 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.