The Effect of Radiation Damage on Mechanical Properties

As shown in the previous chapter, radiation by high energy particles such as neutrons, protons or ions causes the formation of a variety of defects in the target material. These include vacancy and self-interstitial clusters, dislocation loops, stacking fault tetrahedra (SFT), voids, bubbles, etc. As these defect features modify the matrix of the irradiated material, they distort the lattice and create elastic fields around them, which interact with dislocations in the material and cause changes in their mechanical properties. Often, these changes include an increase in yield and tensile strength, accompanied by a decrease in toughness and ductility. Apart from that, they also affect other features of mechanical behaviour such as yield point phenomena, homogeneous plastic deformation and strain hardening rate. There are also changes in the propensity to undergo stress corrosion cracking. In this chapter, we shall give a brief introduction to the mechanical properties of metals in general, followed by factors leading to strengthening of the material. Following this, we shall have a short survey of the changes in mechanical properties of metals effected by radiation damage.