The strengthening of metals by dispersed particles

Abstract

A review is made of the yield strength attainable by dispersing particles in a metal matrix in order to hinder dislocation motion. The advantages and drawbacks of the various methods used to introduce the particles are considered. The greatest strengths are found in materials containing a large volume fraction of dispersed phase coupled with a high density of dislocations in the matrix. The greatest strengths should be achieved if the dispersed particles are very strong and are loaded to fracture. To load the particles they must be needle-shaped. Experiments on model systems of a metal containing wires to simulate the strong phase are described. These indicate some of the conditions necessary to obtain maximum strength and suggest how extreme brittleness can be avoided.