Physics and phenomenology of strain hardening: the FCC case

Kinetics of flow and strain-hardening☆

Precipitation hardening has long been used to increase the strength of commercial alloys, such as quenched and tempered steels and the duralumin type aluminium alloys. The theoretical treatments of precipitation hardening are briefly considered. The equations for strengthening by ‘hard’ indeformable particles and by ‘soft’ deformable particles are presented, and the implications are discussed. These lead to the concept of an optimum particle size for a given system, but the optimum can vary from system to system depending upon the particle characteristics. A broad comparison is made between the increments in strength that occur due to precipitation in commercial alloys and the predictions of the theories; an important contribution to these increments in strength is shown to derive from variations in the volume fraction of precipitated particles that can be employed in the various systems.

Precipitation hardening in metals

On the Zener drag

Effect of interstitial solutes on the strength and ductility of titanium

The detailed movement of a dislocation line through a random array of point obstacles in the glide plane has been examined, using a digital computer, on the basis of the line tension approximation. The breakaway criterion at each obstacle is a critical angle between the arms of the dislocation, corresponding to a critical force on the obstacle. The shear stress required to move the dislocation through the array has been determined for the complete range of breaking angles 0 to π and the result expressed in an empirical form. The dislocation is observed to move often by an 'unzipping' mechanism involving consecutive breakaway from obstacles on the dislocation. For weak obstacles the critical shear stress is appreciably less than for a regular array of the same density and corresponds exactly with the Friedel relation for the spacing of obstacles on a dislocation. For strong obstacles the dislocation motion is characterized by encircling movements and the severance of many closed loops, and the cri...

Dislocation movement through random arrays of obstacles

A computer program that determines the stress required to move a dislocation through an array of obstacles distributed at random on a slip plane has been written. This program has been used to meas...

A. J. E. Foreman

Papers

Dislocation movement through random arrays of obstacles

Dislocation movement through random arrays of obstacles