| Mechanically alloyed Ni₃Al and ODS Ni₃Al powders were consolidated by hot extrusion. The microstructures of as-extruded and heat-treated Ni₃Al and ODS Ni₃Al were observed by transmission electron microscopy, electron energy-loss spectroscopy, energy-dispersive X-ray spectroscopy and optical microscopy. Fine oxide dispersoids were uniformly distributed in as-extruded both Ni₃Al and ODS Ni₃Al materials. EELS and EDS analysis showed that fine dispersoid in Ni₃Al is α-Al₂O₃. The dispersoid volume fraction was 3.6% in Ni₃Al, and 4.5% in ODS Ni₃Al. The Y₂O₃ added in ODS Ni₃Al reacted with Al₂O₃ and formed YAG, Y₃Al_5O_(12). The size measurement of dispersoid in Ni₃Al and ODS Ni₃Al annealed at 1100℃ for 2 to 30h showed that the dispersoids coarsen by diffusion-controlled mechanism. In addition, the growth kinetic constants of oxide dispersoids in Ni₃Al and ODS Ni₃Al were 1.31×10^(-27)㎥/sec. 1.67×10^(27)㎥/sec, respectively. |
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