Normal Vs Abnormal
In common with recovery and recrystallisation, growth phenomena can be separated into continuous and discontinuous mechanisms. In the former the microstructure evolves from state A to B (in this case the grains get larger) in a uniform manner. In the latter, the changes occur heterogeneously and specific transformed and untransformed regions may be identified. Discontinuous grain growth is characterised by a subset of grains growing at a high rate and at the expense of their neighbours and tends to result in a microstructure dominated by a few very large grains. In order for this to occur the subset of grains must possess some advantage over their competitors such as a high grain boundary energy, locally high grain boundary mobility, favourable texture or lower local second-phase particle density.
Read more about this topic: Grain Growth
Famous quotes containing the words normal and/or abnormal:
“Unlike the normal pattern, I know I have grown more liberal as I’ve grown older. I have become more convinced that there is room for improvement in the world.”
—Walter Wellesley (Red)
“Your Englishman, confronted by something abnormal will always pretend that it isn’t there. If he can’t pretend that, he will look through the object, or round it, or above it or below it, or in any direction except into it. If, however, you force him to look into it, he will at once pretend that he sees the object not for what it is but for something that he would like it to be.”
—James Agate (1877–1947)