13th International Conference on Fracture June 16–21, 2013, Beijing, China -6- from 475 to 470 °C also coincides with the brittle fracture behavior and the eutectic solidification domain. One can also notice that the alloy starts to become sensitive with respect to displacement rate, the largest sensitivity at the lowest temperatures. In addition, one can observe that the error bars (standard deviation) are larger when the sample becomes brittle and smaller if it is ductile. Figure 5. Comparison in peak forces between two different displacement rates at different temperature points (left vertical axis) and corresponding solid fractions (right vertical axis). The error bars are shown; when not visible they are smaller than the size of the data point. The ductility of the alloy at different temperature points is shown in Figure 6. For both displacement rates, one can see that the ductility of the alloy starts to drop significantly as the temperature increases above 465 °C. The lowest ductility value for both displacement rates was found at a temperature of 475 °C or fs = 0.94, which corresponds, according to the solidification path in Figure 2, to the beginning of the eutectic solidification. As the temperature increases further above 475 °C, the ductility starts to develop gradually up to 550 °C. If extrapolated to higher temperatures, the temperature dependence of the ductility points would resemble the shape of the classical brittle temperature range curve [8]. Figure 6. Comparison of the ductility of the alloy at different temperature points (left vertical axis) with respect to its respective solid fraction of the alloy (right vertical axis).
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