13th International Conference on Fracture June 16–21, 2013, Beijing, China -3- Figure 2. The solidification path of an AA7050 alloys as calculated by JMat-Pro software (Scheil calculation). The test temperatures that we used in this work corresponded to solid fractions (fs) between 0.85 and 1.0. We took data at several points within this range such as at 0.85, 0.88, 0.9, 0.94, 0.97, 0.99 and 1.0 or in terms of temperature – at 550, 520, 485, 475, 473, 470 and 465 °C, respectively. The solidification path of this alloy was calculated by JMat-Pro software and is shown in Figure 2, the vertical lines in such a figure show the temperature points where we performed the data acquisitions. To observe the displacement-rate sensitivity behavior of the alloy in this temperature range, we used two different displacement rates. For each combinations of the test (temperature–displacement rate), we repeated the test three to four times to obtain statistical information of the test. The fracture surface of the samples was observed in a Jeol JSM-6500F scanning electron microscope (SEM) at the tip of the failed specimens. 3. Results and discussion 3.1 Mechanical properties From the tensile tests, we obtained force–displacement curves at different temperature points and displacement rates. The force–displacement curves with a displacement rate of 0.2 mm/min are shown on Figure 3 and with a displacement rate of 2 mm/min, on Figure 4. Due to the large scaling range of the force value, at the displacement rate 0.2 mm/min, we divided the entire data into two sets: The data from fs = 1.0 down to fs = 0.97 are shown in Figure 3a and the data from fs = 0.97 down to fs = 0.85 are shown in Figure 3b. Figure 3 shows that at the displacement rate 0.2 mm/min, the height of the peak force in general
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