Microstructural features play a big role in how materials break. There are two main ways materials fail: ductile and brittle. Let’s break down some important factors that affect these failures.

1. Grain Size:

   • When grains in a material are smaller, it makes the material stronger. This is called the Hall-Petch relationship.
   • Smaller grains can help prevent ductile failure. This type of failure often happens when grains are around 10 micrometers or smaller.

2. Phases:

   • Some materials have different phases, and this can lead to brittle failures. Phase boundaries can gather stress, making the material more likely to break.
   • For example, ceramics tend to break in a brittle way about 70-90% of the time when stretched.

3. Crystallographic Orientation:

   • Some materials behave differently depending on which way they are under stress. Anisotropic materials, for instance, can become more brittle when they are tired from too much use.
   • These tired materials can show a 60% increase in brittleness when stressed in certain directions.

In general, when materials break in a ductile way, they stretch and can elongate by 95%. On the other hand, brittle fractures usually break with hardly any stretching, showing less than 5% elongation.