ly 3.5 µm in length which is comparable to the particle sizes observed in Figure 10. Therefore, the AlB2
Figure 12A was believed to be AlB2 analysis is in Figure 12B. The AlB2
particle was be-
lieved to also aid in grain refinement by providing nucleating sites and restricting grain growth. As shown in Figure 13A, a group of TiB2
lieved to be the nucleating source for the Mg grain. Similar to the casting treated with Al-5Ti-1B, TiB2
was be-
particles. The Mn-Al particles may have interfered with nu- cleation and reduced the refining potential of Al-1Ti-3B. With Al-5Ti-1B grain refiner addition, the TiB2
particles (EDX analysis in Figure 13B) were observed at the center of an AZ91E casting treated with Al- 1Ti-3B. The TiB2
particles were observed alongside Mn-Al particles were not
The addition of the Al-1Ti-3B grain refiner also introduced solute Ti into the Mg alloy. It was expected that all the Ti within the salts would react to form TiB2
, but the TEM im-
. The corresponding EDX particle was approximate-
grain refining potential of Al-1Ti-3B. The image in Figure 14A was a high concentration (5 wt.%) Al-1Ti-3B sample used to confirm that the TiB2
observed alongside Mn-Al particles as shown in Figure 8. The clustering of Mn-Al with TiB2
could be reason for the reduced particles (verified using EDX
analysis shown in Figure 14B) segregated to the grain bound- aries in a manner similar to the Al-5Ti-1B sample in Figure 9.
TEM Analysis AZ91E + Al-1Ti-3B
(a) (b)
Figure 12. SEM image of AZ91E + 1.0 wt.% Al-1Ti-3B after five minutes of holding (a) AlB2 at center of grain and (b) EDX analysis of AlB2
particle. particle
(b) (a)
Figure 13. SEM image of AZ91E + 1.0 wt.% Al-1Ti-3B showing TiB2 particle (a)TiB2
nucleating particle and (b) EDX analysis of TiB2 International Journal of Metalcasting/Spring 11 nucleating particle. 37
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88