PSI - Issue 71

Gnaneshwar Sampathirao et al. / Procedia Structural Integrity 71 (2025) 484–491

488

Fig. 5. Evolution of hardness values for Aluminium single crystal indentation on (110) surface

Table 1. Different types of dislocations formed when indented on Al single crystal with (110) orientation

Dislocation type

Segments

Dislocation type

Segments

Dislocation type

Segments

Others Perfect

20

Others Perfect

14

Others Perfect

20

3

1

2

Shockley Stair-rod

70

Shockley Stair-rod

67 19

Shockley Stair-rod

75 13 10

9 8 2

Hirth Frank

Hirth Frank

3 2

Hirth Frank

4

3.3. Effect of Grain Size and Boundary Now, it can be seen the influence of grain boundaries on the mechanical response by considering bi-crystal configurations formed by (100) and (110) grains. Our earlier findings indicated that the (100) orientation tends to form perfect dislocations, whereas the (110) orientation facilitates more partial dislocations. At the grain boundary, stress fields and lattice orientations differ significantly from those in a single crystal. From Fig. 6, it has been observed that at lower indentation velocities, perfect dislocations dominate. As the velocity increases, imperfect dislocations, such as Shockley partials, become more prevalent. Table 2. Hardness values vs grain size with (100) or (110) orientation Al grains at dimensions 150x150x150 Å, 200x200x200 Å, 300x300x300 Å to study the size effect

Constraints

Hardness (eV/ Å 3 )

150 Å, (100) 150 Å, (110) 200 Å, (100) 200 Å, (110) 300 Å, (100) 300 Å, (110)

0.0046 0.2518 0.1972 0.0046 0.2083 0.3280