CES Information Guide - Materials Science Engineering

M A T E R I A L S C I E N C E & E N G I N E E R I N G

Background
Material Classes

Material Structure

Bonding

Crystalline

Amorphous

Microstructure

Physical Properties

Material Selection

Material Processing

Example Case Studies

Microstructure

Microstructure are material structures seen at the micro level. Specifically, they are structures of an object, organism, or material as revealed by a microscope at magnifications greater than 25 times.

When typically mentioned, the microstructure are defects, impurities, grains, and grain boundary. Simply put, anything that is not regular from a given crystalline structure is a microstructure. Useful definitions below:

Defects in general are simply errors or interruptions in the uniform crystalline lattice.
Impurities are atoms (like dirt) that don't belong in the regular crystalline structure.
Grains are pure crystals or uniform sections of crystal growth.
Grain boundaries are boundaries around the separated grains.

The following pictures are examples of microstructure that result from specific material processing. The microstructure pictures were supplied by Metaltest, Inc (a materials testing laboratory).

Carburized 1215 Steel - increased hardness (note size of indents) due to additional carbon disfusion into metal.

Gray Cast Iron - typical microstructure of gray iron is a matrix of pearlite with graphite flakes dispersed throughout.

6-4 Titanium - oxygen enriched surface due to heat treatment process.

See if you can find defects, impurities, grains, and grain boundaries in this microstructure. You can tell a lot about a material from it's microstructure.