Plastic deformation of metals and alloys

This chapter focuses on relationships between plastic deformation structures and mechanical properties in metals and alloys deforming by dislocation glide. We start by summarizing plastic deformation processes, then look at the fundamental mechanisms of plastic deformation and explore how deformation structures evolve. We then turn to experimental techniques for characterization which have allowed deformation microstructures to be quantified in terms of common structural parameters. The microstructural evolution has been described over many length scales and analyzed theoretically based on general principles. The deformation microstructures are related to work hardening stages. Finally we identify correlations between a wide range of microstructural features and mechanical properties, particularly flow stress, and use experimental observations to illustrate their inter-relationships.

Properties of tetrahedral amorphous carbon prepared by vacuum arc deposition

The structural, optical, electrical and physical properties of amorphous carbon deposited from the filtered plasma stream of a vacuum arc were investigated. The structure was determined by electron diffraction, neutron diffraction and energy loss spectroscopy and the tetrahedral coordination of the material was confirmed. The measurements gave a nearest neighbour distance of 1.53 Å, a bond angle of 110 and a coordination number of four. A model is proposed in which the compressive stress generated in the film by energetic ion impact produces pressure and temperature conditions lying well inside the region of the carbon phase diagram within which diamond is stable. The model is confirmed by measurements of stress and plasmon energy as a function of ion energy. The model also predicts the formation of sp2-rich materials on the surface owing to stress relaxation and this is confirmed by a study of the surface plasmon energy. Some nuclear magnetic resonance, infrared and optical properties are reported and the behaviour of diodes using tetrahedral amorphous carbon is discussed. © 1991.