Properties of most of the materials are tremendously influenced by some
imperfections or defects. These imperfections greatly alter the mechanical, electrical,
surface, chemical, and thermal properties of materials. Therefore, one should have
complete knowledge of defects or imperfections. The mechanical properties of pure
metals greatly change when they are alloyed; for example, steel (a combination of iron
and 0.1% carbon) is much harder and stronger than pure iron. Bronze (20% tin and
80% copper by mass) produces a much harder and sharper weapon than pure tin or pure
copper. Jewelry gold (pure gold and 5% copper by mass) is a much harder, lustrous,
and durable gold than pure gold.
Keywords: Dispersion strengthening, Edge and screw dislocations, Frenkel
defect, Grain boundary defect, Grain boundary strengthening, Line defects, Point
defects, Plane defects, Precipitation hardening, Schottky defect, Solid solution
hardening, Strain hardening, Twin boundary defect, Volume defects.
