Title: Evolution of the secondary α phase morphologies during isothermal heat treatment in Ti-7333 alloy
Abstract: Evolution of the secondary α phase morphologies during isothermal heat treatment of a near β titanium alloy Ti–7Mo–3Al–3Nb–3Cr (Ti-7333) has been studied by using SEM and TEM. The results indicated that the morphologies of α phase widely varied by changing the isothermal temperature and time. The needle-like secondary α precipitate morphology formed after solution treatment above β transus followed with aging treatment. When the aging temperature reduced, the length and width of α phase reduced while the volume fraction increased. This increasing in the volume fraction of α phase resulted in the strengthening of the micro-hardness of the alloy. In addition, the results showed that there was almost no precipitation after 1 min isothermal holding time at 650 °C. After 2 min, α phase presented a dot shape precipitation with a nonuniform distribution. Increasing the holding time to 5 min, the α precipitation demonstrated a needle-like shape. At last, the coarse α precipitation formed after aging 3 h. The volume fraction of α increased from 4.6% to 44% while the aging time increasing from 2 min to 3 h. The effect of the alloy elements on governing the microstructure is discussed.
Publication Year: 2013
Publication Date: 2013-07-10
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 54
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