Strain on amorphous materials

A number of properties of amorphous materials including fatigue, fracture and component performance are governed by the magnitude of strain fields around inhomogeneities such as inclusions, voids and cracks. Localized strain information was only available from surface probes such as optical or electron microscopy. Universal diffraction method for characterizing bulk stress and strain fields in amorphous bulk metallic glass was presented by Poulsen et al. The macroscopic response is shown to be less stiff than the atomic next-neighbour bonds because of structural rearrangements at the scale of 4–10Å. The method is also applicable to composites comprising an amorphous matrix and crystalline inclusions.

Example of raw data with polar coordinates (s,η).

Evolution of strain components during uniaxial compression of a homogenous specimen. Components ε11 (square), ε12 (diamond), and ε22 (circle), resulting from an analysis based on the shift of the first peak shown in image.

Poulsen H.F., Wert J.A., Neuefeind J., Honkimäki V., Daymond M. - Measuring strain distributions in amorphous materials - Nature Materials 4, 33-36 (2005).