Read Section 79 of book and answer the following Figure 717b

Read Section 7.9 of book and answer the following Figure 7.17b shows possible location of smaller substitutional impurity in the vicinity of edge dislocation. Explain in terms of strain fields why the smaller substitutional atoms would be situated in that position. Why does presence of substitutional atoms (smaller or larger) increase resistance to slip?

Solution

a)

Smaller substitutional atoms are suited to stablize the other atoms and to have minimum energy to get stability.

b)

Substitutional atoms are areas of discontinuity so they restict the movement of dislocation which is the mechanism to slip. So slip decreases and hardness increases.