| Phase Boundary Migration in DCB. (cont.) |
Click image to enlarge (~1MB) |
| 56 and 57.
The
brown and green beta grains are nearly gone. See the blocky
subgrains that have developed in the blue grain. Following image 57, about five hours after alpha growth was started, the temperature was put up again. Image 58 will show what this field of material looked like after only a few minutes in the beta field, at a temperature of about 42°C. What behavior is expected of the brown and green grains? (ans) |
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| 58.
Your prediction is correct! See the hang-up embayments pointing
opposite to the direction of phase boundary migration, for example at
(40,40). See how the brown and green grains are now much more
idioblastic (when they are growing) than they were a moment ago (when
they were shrinking). Do you think the old pink beta porphyroblast situated around (80,30) in this field of view will come back again if we hold the temperature in the beta field long enough? |
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