Strain-generated active paths

Fig. 8.2 Strain-generated active path mechanisms, (a) Often referred to as the film rupture model and (b) the slip step dissolution model. In both cases growth is by dissolution film rupture is the rate controlling step, not the mechanism of crack growth...

Figure 4.43 Strain generated active path mechanisms (A) Film rupture model (B) slip step dissolution model. (From Sedriks, A.J., Slattery, P.W. and Pugh, E.M. (1969). Trans. Am. Soc. Met, 62, 1238. Reproduced by kind permission of ASM, Metals Park, Ohio, USA)...

Explain the main difference between the preexisting active path, strained generated active paths and specific adsorption theories. 

Active path (strain generated) If the protective film is disrupted, the exposed metal is attacked until the disrupted film is again formed. As a result of disruption of the protective films, the metal becomes active. The plastic strain in the underlying metal is responsible for disrupting the film. This type of disruption provides a strain generated active path. 

Transgranular fracture C steel in C03-HC03 (higher strain rates) along strain-generated Ni steels in MgCl2, C steel in CO-C02-H20 active paths C and low alloy steels in liquid NH3... 

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