PSI - Issue 14

Ashish Mishra et al. / Procedia Structural Integrity 14 (2019) 544–548 A.Mishra, A. Alankar / Structural Integrity Procedia 00 (2018) 000–000

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was subjected to constant tensile strain rate of 1000 s -1 . The initial dislocation density of F-R sources in the crystal was ~10 12 m/m 3 . The material properties of copper crystal used in simulation have been taken from Akarapu et al. (2010) and are presented in Table 1. For this strain rate, the time step was maintained constant at 10 -10 s throughout the DD simulation. The simulations were carried out for 1 Million steps each.

Table 1. Material properties and parameters controlling DD simulation. Parameters description Values Shear modulus (Pa) 4.83×10 10 Density (kg/m 3 ) 8960 Poisson's ratio

0.3 10000 300 0.04

Mobility (Pa -1 s -1 ) Temperature (K) Stacking fault energy (J/m 2 )

3. Results and discussions 3.1. Dislocation density evolution on active slip systems

Initial yielding in FCC crystals depend upon crystallographic orientation. The 12 slip systems in an FCC crystal possess distinct Schmid factors depending on the crystallographic orientation of crystal. According to Schmid's law, only 6 out of 12 slip systems in FCC crystal should be active when the tensile axis is aligned along (111) crystallographic direction. From Fig. 1, it is evident that dislocations activity can be seen on 6 slip systems as the dislocation density varies in these slip systems only while the rest systems have constant dislocation density.

Fig. 1. Evolution of dislocation density on different slip systems when tensile axis is aligned along [1 1 1] direction w.r.t strain.