![]() ![]() This result points very specifically to the importance not just of particle coarsening but also of particle dissolution because of the requirement that the temperature approach the solvus. It is even more clear in the work on aluminum–copper by Calvet and Renon (1960) who showed that abnormal grain growth occurred at temperatures within about 30° of the solvus (for dissolution of the theta phase) but not above it ( Fig. ![]() This is clearly shown in the classic early work of May and Turnbull (1958) on the effect of MnS particles on abnormal grain growth in silicon–iron. Strong evidence for this comes from the large number of experimental observations, which show that abnormal grain growth is particularly likely to occur as the annealing temperature is raised and as the particle dispersion becomes unstable. The occurrence of abnormal grain growth may be limited by “nucleation” rather than growth considerations. 11.44), it may be seen that AGG is not possible in materials 1 or 2, but is highly likely in materials 3 and 4. If the measured grain sizes are compared with D M, the critical grain size for AGG ( Eq. It can be seen that particularly for the material showing retarded recrystallization (material code 1), the measured grain size is very much larger than the limiting grain size D SZ as given by Eq. Data for two specimens from each investigation (the extreme data points of each figure) are summarized in Table 11.3. ![]() As an example, consider the recrystallization data shown in Figs. 9.2 and 9.3 Fig. 9.2 Fig. 9.3 for particle-containing aluminum alloys which exhibit accelerated and retarded recrystallization. As discussed in Section 9.2.1, the grain size produced by primary recrystallization is a complex function of the particle parameters and the thermomechanical processing route, and in alloys in which the ratio F v/ r is large, particle pinning often results in a large grain size after primary recrystallization. ![]() According to the analysis above, abnormal grain growth will not be possible if the grain size is larger than four times the limiting grain size for normal grain growth. Since the amount of substance stays equal, you can calculate the volume of your final solution $V_\mathrm.In many cases the grain size produced during primary recrystallization is significantly greater than the particle-limited grain size, and Hillert (1965) noted that this is a very effective way of suppressing abnormal grain growth. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. Archives
December 2022
Categories |