Elements of Metallurgy and Engineering Alloys

edited by F.C. Campbell








640+ pages

Selected Contents

Part 1: Physical and Mechanical Metallurgy

Chapter 1 – Metallic Structure

  • Periodic Table
  • Bonding in Solids
    • Metallic Bonding
    • Ionic Bonding
    • Covalent Bonding
    • Secondary Bonding
  • Crystalline Structure
    • Space Lattices and Crystal Systems
    • Face-Centered Cubic System
    • Hexagonal Close-Packed System
    • Body-Centered Cubic System
  • Slip Systems
  • Allotropy

Chapter 2 – Crystalline Imperfection and Plastic Deformation

  • Point Defects
  • Line Defects
  • Plastic Deformation
    • Dislocations and Plastic Flow
    • Work Hardening
  • Surface or Planar Defects
    • Grain Boundaries
    • Polycrystalline Metals
    • Phase Boundaries
    • Twinning
    • Stacking Faults
  • Volume Defects

Chapter 3 – Solid Solutions

  • Interstitial Solid Solutions
  • Substitutional Solid Solutions
  • Ordered Structures
  • Intermediate Phases
  • Dislocation Atmospheres and Strain Aging

Chapter 4 – Introduction to Phase Transformation

  • Free Energy
  • Kinetics
  • Liquid-Solid Phase Transformations
  • Solid-State Phase Transformations
  • Spinodal Decomposition
  • Martensitic Transformation

Chapter 5 – Diffusion

  • Mechanisms of Diffusion
    • Interstitial Diffusion
    • Substitutional Diffusion
  • Fick’s Laws of Diffusion
    • Fick’s First Law of Diffusion
    • Fick’s Second Law of Diffusion
    • Several Applications of Fick’s Second Law of Diffusion
  • Temperature Dependence of Diffusion
  • Intrinsic Diffusion Coefficients (Kirkendall Effect)
  • High Diffusion Paths

Chapter 6 – Phase Diagrams

  • Phase Rule
  • Binary Isomorphous System
  • Eutectic Alloy System
    • Aluminum-Silicon Eutectic System
    • Lead-Tin Eutectic System
  • Free Energy of Alloy Systems
  • Peritectic Reaction
  • Monotectic Reaction
  • Intermediate Phases
  • Solid-State Reactions
    • Eutectoid Reactions
  • Ternary Phase Diagrams

Chapter 7 – Solidification and Casting

  • The Liquid State
  • Solidification Interfaces
  • Solidification Structure
  • Segregation
  • Grain Refinement and Secondary Dendrite Arm Spacing
  • Porosity and Shrinkage
  • Casting Processes
    • Sand Casting
    • Plaster and Shell Molding
    • Evaporative Pattern Casting
    • Investment Casting
    • Permanent Mold Casting
    • Die Casting

Chapter 8 – Recovery, Recrystallization, and Grain Growth

  • Recovery
  • Recrystallization
  • Recrystallization – Temperature and Time
  • Recrystallization – Purity of Metal
  • Recrystallization – Original Grain Size
  • Recrystallization – Temperature of Deformation
  • Grain Growth
  • Normal Grain Growth
  • Abnormal Grain Growth

Chapter 9 – Precipitation Hardening

  • Particle Hardening
  • Theory of Precipitation Hardening
  • Precipitation Hardening of Aluminum Alloys
  • Solution Heat Treating
  • Quenching
  • Aging
  • Dispersion Hardening

Chapter 12 – Mechanical Behavior

Chapter 13 – Fracture

Chapter 14 – Fatigue

Chapter 15 – Creep

Chapter 16 – Deformation Processing

Chapter 17 – Physical Properties of Metals

Chapter 18 – Corrosion

Part II: Engineering Alloys

Chapter 26 – Aluminum

  • Aluminum Metallurgy
  • Aluminum Alloys Designation
  • Aluminum Alloys
    • Wrought Non-Heat-Treatable Alloys
    • Wrought Heat-Treatable Alloys
  • Melting and Primary Fabrication
    • Rolling Plate and Sheet
    • Extrusion
  • Casting
    • Aluminum Casting Alloys
    • Aluminum Casting Control
  • Heat Treating
  • Annealing
  • Fabrication
  • Corrosion

Chapter 27 – Magnesium and Zinc

Chapter 28 – Titanium


The notes

Chapter 9 contains the best explanation of the essence of precipitation hardening that I have come across.
Here it is.

Precipitation hardening

Precipitation hardening is used extensively to strengthen not only

  • aluminum alloys

but also

  • magnesium alloys
  • nickel-base superalloys
  • beryllium-copper alloys and
  • precipitation-hardening stainless steels.

In precipitation hardening:

  • An alloy is heated to a high enough temperature to take a significant amount of an alloying element into solid solution.
  • It is then rapidly cooled (quenched) to room temperature, trapping the alloying elements in solid solution.
  • On reheating to an intermediate temperature, the host metal rejects the alloying element in the form of fine precipitates that create matrix strains in the lattice.
  • These the fine precipitate particles act as barriers to the motion of dislocations and provide resistance to slip, thereby increasing the strength and hardness.

Particle Hardening

Particle, or dispersion, hardening occurs when extremely small particles are dispersed throughout the matrix. When a dislocation encounters a fine particle, it must either cut through the particle or bow (loop) around it, as shown schematically in Fig. 9.1.

There are two types of particle strengthening:

  • Precipitation hardening. Takes place during heat treatment.
  • True dispersion hardening. Can be achieved by mechanical alloying and powder metallurgy consolidation.

For effective particle strengthening, the matrix should be soft and ductile, while the particles should be hard and discontinuous (Fig. 9.2). A ductile matrix is better in resisting catastrophic crack propagation. Smaller and more numerous particles are more effective at interfering with dislocations motion then lager and more widely spaced particles.

Fig. 9.1 – Paricle-strengthening

Fig. 9.2 –

Precipitation Hardening of Aluminium Alloys

Aluminium alloys are one of the most series of alloys that can be precipitation hardened, including

  • 2xxx (aluminium-copper) alloys
  • 6xxx (aluminium-magnesium-silicon) alloys
  • 7xxx (aluminium-zinc
  • some of the 8xxx (aluminium-lithium) alloys.

Precipitation hardening consists of three steps:

  • Solution heat treating
  • Rapid quenching
  • Ageing

In solution heat treating, the alloy is heated to a temperature that is high enough to put the soluble alloying elements in solution. After holding at the solution-treating temperature long enough for diffusion of solute atoms into the solvent matrix in occur, it is quenched to a lower temperature (e.g., room temperature) to keep the alloying elements trapped in solution. During ageing, the alloying elements trapped in solution precipitate to form a uniform distribution of very fine particles. Some aluminium alloys will harden after a few days at room temperature, a process called natural ageing, while others are artificially aged by heating to an intermediate temperature (Fig. 3).

Fig. 9.3 – Typical age hardening for aluminium:
T1 – natural ageing (room temperature) artificial  underageing (low temperature);
T2 – artificial underageing; T3 – artificial top ageing; T4 – artificial overageing