Structure and manufacturing Properties of Metals Chapter 3 Structure and manufacturing Properties of Metals Crystal structure of metals Role of various imperfections Importance of grain Failure and fracture of metals Ferrous and non-ferrous metals, alloys

Covalent Bond Some Common Features of Materials with Covalent Bonds: Hard Good insulators Transparent Brittle or cleave rather than deform

Metallic bond Some Common Features of Materials with Metallic Bonds: Good electrical and thermal conductors due to their free valence electrons Opaque Relatively ductile

Ionic Bond Some Common Features of Materials with Ionic Bonds: Hard Good insulators Transparent Brittle or cleave rather than deform

Body-Centered Cubic (BCC) Structure Face Centered Cubic (FCC) Structure Hexagonal Close Packed (HPC) Structure

the atoms in rows A and C are no longer aligned cubic lattice structures allow slippage to occur more easily than non-cubic lattices, so hcp metals are not as ductile as the fcc metals.

Defect Interstitial impurity atom Edge dislocation Self interstitial atom Vacancy Precipitate of impurity atoms Vacancy type dislocation loop Interstitial type dislocation loop Substitutional impurity atom

Simple Cubic Lattice showing atomic planes (marked in red) a dislocation is a crystallographic defect, or irregularity, within a crystal structure Simple Cubic Lattice showing atomic planes (marked in red) Edge dislocation Screw dislocation Burgers vector in black, dislocation line in blue.

Edge Dislocation Screw Dislocation

Grain a) Nucleation of crystals b) crystal growth c) irregular grains form as crystals grow together d) grain boundaries as seen in a microscope

Polycrystalline Deformation Atoms along the boundary packed less efficiently Grain Boundary more disordered Polycrystalline Deformation before after