Stress-Strain Relations of Polycrystalline Metals : 1. Stress Fields in a Plastically Deformed Polycrystalline Aggregate

Stress-dependent ultrasonic scattering in polycrystalline materials.

Stress-dependent elastic moduli of polycrystalline materials are used in a statistically based model for the scattering of ultrasonic waves from randomly oriented grains that are members of a stressed polycrystal. The stress is assumed to be homogeneous and can be either residual or generated from external loads. The stress-dependent elastic properties are incorporated into the definition of th...

Self-affine surface morphology of plastically deformed metals.

We analyze the surface morphology of metals after plastic deformation over a range of scales from 10 nm to 2 mm using atomic force microscopy and scanning white-light interferometry. We demonstrate that an initially smooth surface during deformation develops self-affine roughness over almost 4 orders of magnitude in scale. The Hurst exponent H of one-dimensional surface profiles initially decre...

Nanocrystalline metals are by definition polycrystalline structures

with a mean grain size below 100 nm. Fig. 1 shows an image taken in a transmission electron microscope of a high-density nanocrystalline (nc)-Cu sample with a mean grain size of 20 nm. The mechanical behavior of a fully-dense nanocrystalline metal is, compared with its coarse-grain counterpart, characterized by a significantly enhanced yield stress and a limited tensile elongation1,2. A simple ...

The microstructure origin of large strain plastically deformed SiC nanowires

Surprisingly large strain plasticity has been demonstrated for ceramic SiC nanowires through in-situ deformation experiments near room temperature. This article reports a detailed electron energy-loss spectroscopy (EELS) study of deformation-induced localized plastic zones in a bent SiC nanowire. Both the “red shift” of the plasmon peak and the characteristic fine structure at Si L-edge absorpt...

Infrared Technique for Measuring Ultrasonic Absorption in Polycrystalline Metals