Plastic Deformation at Micron and Submicron Scales

Marisol Koslowski, Mechanical Engineering Purdue University

Most people experiences the way objects plastically deform on a macroscopic scale. From a car crash to the bending of a paper clip plastic deformation occurs in the form of a smooth flow as a response of an applied stress. But due to the constant shrinking on the dimensions of mechanical devices -such as microelectromechanical systems (MEMS) and micro electronic interconnects, and the design of materials with tailored nanostrucutre- the notion that plasticity is governed not by a steady flow but by the occurrence of intermittent avalanches of defects moving through the material is gaining increasing attention.

To model the deformation of metallic materials at micron and submicron scales a continuum theory of dislocations is derived. Our simulations show the formation of structures and their influence in macroscopic deformation and the dependence on the yield stress on the characteristic size of the sample, known as Hall-Petch effect.

We also study the jerky character of dislocation motion and its analogy to earthquakes, biological systems and other systems showing critical behavior.

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