Lamellae secondary

As the ageing time was increased, the initial transformation product (identified as primary lamellae with a spacing less than lOnm) was gradually replaced by secondary lamellae with a larger spacing, typically several tens of nanometres (Figure 5.20). 

Figure 5.21 shows the results of an analysis trace made across the primary lamellae/ secondary lamellae interface shown in Figure 5.20 as the line X-X. 

Figure 5.20. TEM micrograph of Co-32 wt%W alloy aged at 875 K for 3 days, showing fine primary lamellae having been replaced by coarser secondary lamellae. (Reproduced with permission by Zieba...

Figure 5.21. Composition profile across the primary7 secondary lamellae boundary shown in Figure 5.20 (line X-X). (Reproduced with permission of Zieba et al. 1997.)...

Handy, R. D. and Eddy, F. B. (1991). The absence of mucus on the secondary lamellae of unstressed rainbow trout, Oncorhynchus mykiss (Walbum), J. Fish Biol., 38, 153-155. 

Cross-hatching produces edges along the lines where the oblique secondary lamellae touch the primary crystallites. Exactly these edges can be directly related to the observed deviation. A theoretical analysis gives the following result... 

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