Particle Strengthening

1. Particle Strengthening: Overview
2. Particle Strengthening: Introduction
3. Particle Spacing
4. Lattice Parameter
5. Coherent and Incoherent Particles
6. Dislocation/Precipitate or Particle Interactions I
7. Dislocation/Precipitate or Particle Interactions II
8. Orowan Equation I
9. Particle Size and Volume Fraction
10. Orowan Equation II
11. Towards an Improved Prediction
12. Orowan Equation III
13. Orowan Equation IV
14. An Empirical Approach
15. Increase in Flow Stress Determination
16. Increase in Flow Stress Determination II
17. Summary

In this module, the principles underlying strengthening by particles are reviewed and applied to steels.

A knowledge of the line tension and the orientation of a dislocation line is also essential. Whilst some familiarity of crystal structure is needed, concepts relating to particle/matrix interfaces are introduced.

Learning Outcomes for this Section

After completing this section, you should be able to:

• Describe the effects of particle volume fraction, spacing and size on strength and toughness
• Quantify the effects of particle volume fraction, spacing and size on strength and toughness
• Have an appreciation of how to measure particle volume fraction, spacing and size using electron microscopy.

Pre-Requisites

Before starting, it is important that you are familiar with the following terms:  Yield stress; Crystal system; Dislocation; Burgers vector; Transmission Electron Microscopy (External site); Stress field; Work hardening;

You should be familiar with the concepts covered in:

• Tensile Test

References

• Dieter, GE,  Mechanical Metallurgy, McGraw Hill, 0071004068 
• Gladman, T,  The Physical Metallurgy of Microalloyed Steels, Institute of Materials, 0 901716 81 2 
• Cottrell, AH,  Dislocations and Plastic Flow in Crystals, OUP,  
• Friedel, J,  Dislocations, Pergamon Press,  
• Newbach, E,  Particle Strengthening of Metals and Alloys, Wiley,  
• McLean, D,  Mechanical Properties of Metals, Wiley,  
• Kelly, A & Nicholson, RB,  Strengthening Mechanisms in Crystals, Elsevier Publishing,  
• Reed-Hill, RE & Abbaschian, R,  Physical Metallurgy Principles, PWS,  
• Smallman, RE & Bishop, RJ,  Modern Physical Metallurgy, Elsevier Publishing,  
• Bhadeshia, HKDH & Honeycombe, RWK,  Steels: Microstructure and Properties, Arnold,