The formation of ordered clusters in Ti-7Al and Ti-6Al-4V

A. Radecka; P.A.J. Bagot; T.L. Martin; J. Coakley; V.A. Vorontsov; M.P. Moody; H. Ishii; D. Rugg; D. Dye

doi:10.1016/j.actamat.2016.03.080

The formation of ordered clusters in Ti-7Al and Ti-6Al-4V

A. Radecka, P.A.J. Bagot, T.L. Martin, J. Coakley, V.A. Vorontsov, M.P. Moody, H. Ishii, D. Rugg, D. Dye^*

^*Corresponding author for this work

Design, Manufacturing And Engineering Management

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Abstract

Ti-Al alloys can suffer from a chemical decomposition on ageing around 500°C or on air cooling. At long ageing times this results in the formation of α₂ (Ti₃Al) precipitates. At reduced times or elevated temperatures, diffuse electron or neutron diffraction peaks can be observed, which has been termed 'short range ordering' (SRO). Here, we present correlative transmission electron microscopy (TEM) and atom probe tomography (APT) results showing that the reaction proceeds through the formation of ordered Al-rich precipitate clusters. Notably, Al-Al clustering could be observed well before the appearance of distinct precipitates in the TEM. In addition, the V-containing α phase of Ti-6Al-4V formed ordered clusters much faster than in binary Ti-7Al. This implies that the ternary addition of β stabilisers exacerbates the problem of α₂ precipitate formation in commercial dual phase titanium alloys.

Original language	English
Pages (from-to)	141-149
Number of pages	9
Journal	Acta Materialia
Volume	112
Early online date	18 Apr 2016
DOIs	https://doi.org/10.1016/j.actamat.2016.03.080
Publication status	Published - 15 Jun 2016

Funding

This research was supported by a Rolls-Royce plc – EPSRC CASE studentship. Material for the study was provided by Timet. Helpful discussions with Prof. T.C Lindley, Prof. G.D.W. Smith, Prof. M.H. Loretto and Prof. I.P. Jones are gratefully acknowledged. Experimental assistance was generously provided by Prof. J.P. Bradley, Dr K.M. Rahman, Dr C. McGilvery, Dr M. Ardakani and Dr D. Isheim. VV and JC would like to acknowledge support from an EPSRC doctoral prize fellowship , EU Marie Curie fellowship respectively. DD was supported by EPSRC grants EP/K034332/1 and EP/H004882/1 .

Keywords

atom probe tomography (APT)
ordering
titanium alloys
transmission electron microscopy (TEM)

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10.1016/j.actamat.2016.03.080

Radecka-etal-AM-2016-The-formation-of-ordered-clusters-in-Ti-7Al-and-Ti-6Al-4VAccepted author manuscript, 14.1 MBLicence: CC BY-NC-ND 4.0

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title = "The formation of ordered clusters in Ti-7Al and Ti-6Al-4V",

abstract = "Ti-Al alloys can suffer from a chemical decomposition on ageing around 500°C or on air cooling. At long ageing times this results in the formation of α2 (Ti3Al) precipitates. At reduced times or elevated temperatures, diffuse electron or neutron diffraction peaks can be observed, which has been termed 'short range ordering' (SRO). Here, we present correlative transmission electron microscopy (TEM) and atom probe tomography (APT) results showing that the reaction proceeds through the formation of ordered Al-rich precipitate clusters. Notably, Al-Al clustering could be observed well before the appearance of distinct precipitates in the TEM. In addition, the V-containing α phase of Ti-6Al-4V formed ordered clusters much faster than in binary Ti-7Al. This implies that the ternary addition of β stabilisers exacerbates the problem of α2 precipitate formation in commercial dual phase titanium alloys.",

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author = "A. Radecka and P.A.J. Bagot and T.L. Martin and J. Coakley and V.A. Vorontsov and M.P. Moody and H. Ishii and D. Rugg and D. Dye",

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T1 - The formation of ordered clusters in Ti-7Al and Ti-6Al-4V

AU - Radecka, A.

AU - Bagot, P.A.J.

AU - Martin, T.L.

AU - Coakley, J.

AU - Vorontsov, V.A.

AU - Moody, M.P.

AU - Ishii, H.

AU - Rugg, D.

AU - Dye, D.

PY - 2016/6/15

Y1 - 2016/6/15

N2 - Ti-Al alloys can suffer from a chemical decomposition on ageing around 500°C or on air cooling. At long ageing times this results in the formation of α2 (Ti3Al) precipitates. At reduced times or elevated temperatures, diffuse electron or neutron diffraction peaks can be observed, which has been termed 'short range ordering' (SRO). Here, we present correlative transmission electron microscopy (TEM) and atom probe tomography (APT) results showing that the reaction proceeds through the formation of ordered Al-rich precipitate clusters. Notably, Al-Al clustering could be observed well before the appearance of distinct precipitates in the TEM. In addition, the V-containing α phase of Ti-6Al-4V formed ordered clusters much faster than in binary Ti-7Al. This implies that the ternary addition of β stabilisers exacerbates the problem of α2 precipitate formation in commercial dual phase titanium alloys.

AB - Ti-Al alloys can suffer from a chemical decomposition on ageing around 500°C or on air cooling. At long ageing times this results in the formation of α2 (Ti3Al) precipitates. At reduced times or elevated temperatures, diffuse electron or neutron diffraction peaks can be observed, which has been termed 'short range ordering' (SRO). Here, we present correlative transmission electron microscopy (TEM) and atom probe tomography (APT) results showing that the reaction proceeds through the formation of ordered Al-rich precipitate clusters. Notably, Al-Al clustering could be observed well before the appearance of distinct precipitates in the TEM. In addition, the V-containing α phase of Ti-6Al-4V formed ordered clusters much faster than in binary Ti-7Al. This implies that the ternary addition of β stabilisers exacerbates the problem of α2 precipitate formation in commercial dual phase titanium alloys.

KW - atom probe tomography (APT)

KW - ordering

KW - titanium alloys

KW - transmission electron microscopy (TEM)

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JO - Acta Materialia

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ER -

The formation of ordered clusters in Ti-7Al and Ti-6Al-4V

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