University:
McMaster University
Course:
MATLS 2H04 | Introduction to Materials Engineering
Academic year:

2023
Views:

127

Pages:

1
Author:

Sabrina S.

Basic Material Concepts 7.3 Classification of Materials 4 classes of materials metals - metallic bonding, typically stiff, good electronic conductors ceramics - ionic/covalent bonding, stiff (high Young's modulus), brittle polymers - covalent bonding in chains, weak bonding between chains, less stiff, less strong composites - mixture of 2+ above components, superior properties material properties are dependent on many input parameters atoms in the material nature of the bonding between the atoms crystalline or amorphous phases grain size and distribution of phases Metals atoms arrange in long-range order by metallic bonds based on the preferred atomic arrangement, they form a basic unit cell repeating the atomic arrangement many times over large atomic distances forms grains atoms form unit cells → grains (polycrystalline) simple crystal structures of metals FCC - face centered cubic BCC - body centered cubic HCP - hexagonal close-packed examples of metals with each crystal structure chromium iron (alpha) cobalt titanium (alpha) molybdenum copper zinc gold lead tungsten nickel magnesium platinum silver Ceramics ionic ceramics - e.g. Al2O3, NaCl covalent ceramics - e.g. SiO2 (pure elements (e.g. diamond)) amorphous - atoms with short range order (glass) crystalline - more complicated crystal structures than metals their complex structures makes them brittle It is very difficult to plastically deform ceramics because of their complex structures makes them brittle glass diamond