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in the Al-B and Al-Ti-B
Technical Review and Discussion:
Effects of Al-Ti-B Based Grain Refiners on AZ91E Magnesium Alloy Grain Size and Microstructure A. Elsayed, C. Ravindran, Ryerson University, Toronto, ON, Canada B.S Murty, Indian Institute of Technology Madras, Chennai, India
Reviewer: What are some of the “detrimental inter- metallics” obtained with the use of Al-Ti-B refiners?
Authors: We were referring to the coarse and brittle TiAl3 particles that could form during the synthesis of Al-Ti-B re-
to the formation of TiAl3 formation of AlB2
finers if the Ti:B ratio is equal to greater than 1:2.2 (the ratio of Ti:B in TiB2
or AlB12
is 1:2.2. A higher Ti:B ratio will lead and a lower ratio will lead to the ).
Reviewer: What etchant was used? Was a polar - izer in place for microscopic evaluation?
Authors: The etchant used was a solution of 15 % acetic 40
acid, 10 % distilled water and 75 % ethyl alcohol. The sam- ples were etched for two minutes with slight agitation. No polarizer was in place for the microscopic examination. The relatively large grains made grain boundary observation relatively easy under the microscope.
small enough to capture only the particle?
Reviewer: Regarding Figure 7, how exactly was the stoichi- ometry of TiAl3
from your EDX derived? Was the spot-size
Authors: The EDX analysis only revealed the presence of ti- tanium and aluminum within the particles observed. As men- tioned above, TiAl3
served by Wang et al.11 TiAl3
particles were large enough (> 30 µm) to ensure that the entire spot region was concentrated over the particle surface. This is confirmed by the fact that no magnesium peak was de- tected in the EDX analysis (e.g., Figure 9). The revised text was modified to include the authors reasoning.
particles observed in the present study. The authors concluded that the particles were TiAl3
International Journal of Metalcasting/Spring 11
is greater than 1:2.2, which is the case for Al-5Ti-1B (titanium to boron ratio 5:1, Table 2). In addition, the TiAl3
have a similar morphology to the Ti-Al . For the EDX spot analysis, the
particles form if the titanium to boron ratio particles ob-
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