13th International Conference on Fracture June 16–21, 2013, Beijing, China -8- Figure 8. Pictures of fracture surface analysis using SEM: (a) Examples of broken dendrite arms, (b) example of extra-deformed eutectics, (c) example of layer-like eutectics and (d) examples of features that resemble necking of the interdendritic liquid stretched during fracture. 4. Summary We can summarize the results obtained from the experiments as follows: 1. From the shape of the force–displacement curves, we found that in the range of fs = 1.0 (fully solid) to fs = 0.85, the alloy has three different mechanical behavior regimes; ductile (between fs = 1.0 and fs = 0.99), brittle (between 0.99 and 0.9) and then ductile again (between 0.9 and 0.85). 2. The grain coalescence in AA7050 occurs between fs = 0.94 and fs = 0.97. This is showed by the sharp increase in peak force between the mentioned solid fractions. 3. The alloy has almost no displacement rate sensitivity at high temperatures (below fs = 0.94) but it has positive displacement rate sensitivity starting at fs = 0.94 and at higher solid fractions. 4. The alloy produces a ‘classically’ shaped brittle temperature range curve with the minimum of ductility reached at 475 °C, and the alloy gains again ductility as the liquid fraction increases in the alloy. 5. From SEM fracture surface analyses at different data points showed in Figure 7, it is found
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