Solidification microstructures and calculated phase equilibria in the Ti-Al-Mn system
- Univ. of Nottingham (United Kingdom). Dept. of Materials Engineering and Materials Design
- Rolls Royce plc, Derby (United Kingdom)
- Thermotech Ltd., Guilford (United Kingdom)
The solidification behavior of a number of Ti-Al-Mn alloys has been investigated both experimentally and through CALPHAD methods. The alloys were prepared as 1 kg buttons by plasma arc melting and had a nominally constant Ti:Al ratio of 1.14 with Mn levels of 5, 10, 20 and 30 at.%. X-ray diffraction showed that the phases {gamma}-TiAl, {alpha}{sub 2}Ti{sub 3}Al, {beta}-Ti (Al,Mn) and (Mn,Al){sub 2}Ti are present in the alloys in varying quantities following solidification. The 5 and 10% Mn alloys both comprise transformed lamellar dendrites of {gamma}/{alpha}{sub 2} with interdendritic {gamma}, {beta} and (Mn,Al){sub 2}Ti. The quantity of interdendritic material is significantly greater in the 10% Mn alloy. The 30% Mn alloy contains a large volume fraction of primary (Mn,Al){sub 2}Ti with only a small amount of {gamma}, {beta} and {alpha}{sub 2}. The 20% Mn alloy has acicular plates of (Mn,Al){sub 2}Ti which form a eutectic-like microstructure with the other phases. Melting endotherms, obtained by differential thermal analysis (DTA), for 5 and 10% Mn alloys compare well with CALPHAD calculations. Furthermore the CALPHAD prediction of a eutectic valley between the [{beta} + L] and [(Mn,Al){sub 2}Ti + L] phase fields is consistent with both DTA and microstructural observations on all the alloys.
- OSTI ID:
- 524546
- Journal Information:
- Acta Materialia, Journal Name: Acta Materialia Journal Issue: 7 Vol. 45; ISSN 1359-6454; ISSN ACMAFD
- Country of Publication:
- United States
- Language:
- English
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