Rm. Imayev et al., Effect of grain size and partial disordering on ductility of Ti3Al in the temperature range of 20-600 degrees C, ACT MATER, 47(6), 1999, pp. 1809-1821
The effect of grain size and partial disordering on ductility and how stres
s of an intermetallic Ti3Al was studied in the temperature range of 20-600
degrees C using tension and compression testing. The ductility of the fully
ordered material increased considerably when the grain size decreased from
27 to 0.1 mu m, and, at the smaller grain size, an elongation of 4.8% was
achieved at room temperature. Partial disordering of the crystal lattice le
d to a decrease in ductility at temperatures below 500 degrees C, but had n
o influence on the ductility at 500 or 600 degrees C. The critical grain si
ze at which a brittle-to-ductile transition occurred in the fully ordered m
aterial was determined for each temperature studied. This critical grain si
ze increased as the temperature was increased. It was found that, when the
mean grain size decreased and temperature increased, the fracture mode chan
ged from a brittle transcrystalline mode to a brittle intercrystalline mode
and, finally, to a ductile transgranular mode. The increased ductility was
correlated with an enhanced grain boundary relaxation capability at increa
sed temperatures and decreased gain sizes. (C) 1999 Acta Metallurgica Inc.
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