Abstract
High temperature application of modern Ti-alloys is often limited by their insufficient oxidation resistance at temperatures exceeding 650 °C. One way to overcome this obstacle is application of an overlay coating made of TiAl-based alloys. In this study kinetically sprayed coatings of Ti-46Al-8.5Nb-1Ta (at%) on a commercial alloy IMI-834 were investigated. The feedstock powder fabricated by gas atomization consisted of non-equilibrium α-Ti and β-Ti phases. Heat treatment of the powder at 750 °C triggered transformation to the equilibrium ordered γ-TiAl and α2-Ti3Al phases. Mechanical properties of both the as-atomized and the heat treated powders were tested, showing that the as-sprayed one possesses lower hardness and higher ductility. Since such properties of the as-atomized powder are more suited for kinetic spraying, the as-atomized powder was used for coating fabrication. The as-sprayed coatings inherited the non-equilibrium phases of the atomized powder with significant deformation. The coatings were annealed at 750 °C and immediate transformation to a refined microstructure containing the γ-TiAl and α2-Ti3Al phases was observed in < 20 min. Longer annealing time resulted in significant grain growth and formation of defect-free grains.
| Language | English |
|---|---|
| Pages | 240-249 |
| Number of pages | 10 |
| Journal | Surface and Coatings Technology |
| Volume | 315 |
| DOIs | |
| State | Published - 2017 Apr 15 |
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Keywords
- Coating
- Intermetallics
- Kinetic spraying
- Phase transformation
- Titanium aluminides
ASJC Scopus subject areas
- Chemistry(all)
- Condensed Matter Physics
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Materials Chemistry
Cite this
Formation and subsequent phase evolution of metastable Ti-Al alloy coatings by kinetic spraying of gas atomized powders. / Gizynski, M.; Miyazaki, S.; Sienkiewicz, J.; Kuroda, S.; Araki, H.; Murakami, H.; Pakiela, Z.; Yumoto, A.
In: Surface and Coatings Technology, Vol. 315, 15.04.2017, p. 240-249.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Formation and subsequent phase evolution of metastable Ti-Al alloy coatings by kinetic spraying of gas atomized powders
AU - Gizynski,M.
AU - Miyazaki,S.
AU - Sienkiewicz,J.
AU - Kuroda,S.
AU - Araki,H.
AU - Murakami,H.
AU - Pakiela,Z.
AU - Yumoto,A.
PY - 2017/4/15
Y1 - 2017/4/15
N2 - High temperature application of modern Ti-alloys is often limited by their insufficient oxidation resistance at temperatures exceeding 650 °C. One way to overcome this obstacle is application of an overlay coating made of TiAl-based alloys. In this study kinetically sprayed coatings of Ti-46Al-8.5Nb-1Ta (at%) on a commercial alloy IMI-834 were investigated. The feedstock powder fabricated by gas atomization consisted of non-equilibrium α-Ti and β-Ti phases. Heat treatment of the powder at 750 °C triggered transformation to the equilibrium ordered γ-TiAl and α2-Ti3Al phases. Mechanical properties of both the as-atomized and the heat treated powders were tested, showing that the as-sprayed one possesses lower hardness and higher ductility. Since such properties of the as-atomized powder are more suited for kinetic spraying, the as-atomized powder was used for coating fabrication. The as-sprayed coatings inherited the non-equilibrium phases of the atomized powder with significant deformation. The coatings were annealed at 750 °C and immediate transformation to a refined microstructure containing the γ-TiAl and α2-Ti3Al phases was observed in < 20 min. Longer annealing time resulted in significant grain growth and formation of defect-free grains.
AB - High temperature application of modern Ti-alloys is often limited by their insufficient oxidation resistance at temperatures exceeding 650 °C. One way to overcome this obstacle is application of an overlay coating made of TiAl-based alloys. In this study kinetically sprayed coatings of Ti-46Al-8.5Nb-1Ta (at%) on a commercial alloy IMI-834 were investigated. The feedstock powder fabricated by gas atomization consisted of non-equilibrium α-Ti and β-Ti phases. Heat treatment of the powder at 750 °C triggered transformation to the equilibrium ordered γ-TiAl and α2-Ti3Al phases. Mechanical properties of both the as-atomized and the heat treated powders were tested, showing that the as-sprayed one possesses lower hardness and higher ductility. Since such properties of the as-atomized powder are more suited for kinetic spraying, the as-atomized powder was used for coating fabrication. The as-sprayed coatings inherited the non-equilibrium phases of the atomized powder with significant deformation. The coatings were annealed at 750 °C and immediate transformation to a refined microstructure containing the γ-TiAl and α2-Ti3Al phases was observed in < 20 min. Longer annealing time resulted in significant grain growth and formation of defect-free grains.
KW - Coating
KW - Intermetallics
KW - Kinetic spraying
KW - Phase transformation
KW - Titanium aluminides
UR - http://www.scopus.com/inward/record.url?scp=85013651283&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85013651283&partnerID=8YFLogxK
U2 - 10.1016/j.surfcoat.2017.02.053
DO - 10.1016/j.surfcoat.2017.02.053
M3 - Article
VL - 315
SP - 240
EP - 249
JO - Surface and Coatings Technology
T2 - Surface and Coatings Technology
JF - Surface and Coatings Technology
SN - 0257-8972
ER -