Table of Contents

Materials and Structure




In thinking about how the microstructure of metals and alloys influence dislocation motion, and hence the mechanical properties of these materials, it is useful to remember that the dislocation line has an elastic field associated with it. This field can interact with interstitial or substitutional impurity atoms, small second phase particles (as illustrated), grain boundaries between the crystallites of normal polycrystalline technical materials, and with phase boundaries and surfaces.

In designing a material to be tough and strong, the creation of these barriers to dislocation motion is part of the material scientists palette. In selecting a material based on its properties, care must be taken that subsequent manufacturing processes do not change the number of these barriers and give rise to much changed physical properties.

Manufacturing processes such as bending, soldering, welding, and heat treatment can all change the materials microstructure and hence its mechanical properties.

From: Barrett, Nix, and Tetelman,
"The Principles of Engineering Materials,"
Prentice Hall (1973)