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Phase Equilibria Among β/α/α2/γ Phases and Phase Transformations in Ti-Al-Cr System at Elevated Temperatures

Published online by Cambridge University Press:  12 February 2019

Ali Shaaban Open the ORCID record for Ali Shaaban [Opens in a new window] ,
Hideki Wakabayashi ,
Hirotoyo Nakashima  and
Masao Takeyama
Ali Shaaban*
Affiliation:
School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo, Japan Surface Protection and Corrosion Control Lab., Central Metallurgical Research and Development Institute (CMRDI), EGYPT
Hideki Wakabayashi
Affiliation:
School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo, Japan
Hirotoyo Nakashima
Affiliation:
School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo, Japan
Masao Takeyama
Affiliation:
School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo, Japan
*
*(Email: shaaban.a.aa@m.titech.ac.jp)
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Abstract:

Effects of Cr addition to TiAl alloy on the phase equilibria among β/α/α2/γ Phases and phase transformation pathways within the temperature range of 1523 K∼1073 K were investigated using several alloys in the composition of interest. In between 1473 K and 1373 K, The slope of β/α tie-line in the three-phase coexisting region of β+α+γ remains basically unchanged. However, this slope drastically rotates in a clockwise direction, in between 1373 K and 1273 K and below the eutectoid reaction temperature in the binary system (1400 K). This is a strong indication that α-phase exists even below the 1400 K, i.e. addition of Cr stabilizes α against α2 and the three-phase coexisting region of β+α2+γ at lower temperatures is formed through a ternary eutectoid reaction (α → β+α2+γ) with decreasing temperature. This three-phase tie-triangle moves towards lower Al content in phase diagram. This suggests that Cr addition results in increase of the volume fraction of γ-phase with decreasing temperature even in alloys with low Al content.

Keywords

phase equilibriaphase transformation
Type
Articles
Information
MRS Advances , Volume 4 , Issue 25-26: Processing and Manufacturing , 2019 , pp. 1471 - 1476
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Copyright
Copyright © Materials Research Society 2019 

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References

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