It can be inferred from Fig. 4 (a) that average grain size at the edge continuously decreases from ~8µm at ԑ=1 to 370nm at ԑ=60. The average grain size at ԑ=24 & 60 is nearly the same and thus signifying that grain size is saturated. The fraction of HAGBs (Fig. 4 (a)) also increases from 14% to 91% at ԑ=60. The fraction of HAGBs is observed nearly the same at strain levels ԑ= 12, 24 & 60.