Cobalt-doped Ti-48Al-2Cr-2Nb alloy fabricated by cold compaction and pressureless sintering

Xia, Y., Yu, R., Schaffer, G. B. and Qian, M. (2013) Cobalt-doped Ti-48Al-2Cr-2Nb alloy fabricated by cold compaction and pressureless sintering. Materials Science and Engineering A, 574 176-185. doi:10.1016/j.msea.2013.03.023

Author Xia, Y.
Yu, R.
Schaffer, G. B.
Qian, M.
Title Cobalt-doped Ti-48Al-2Cr-2Nb alloy fabricated by cold compaction and pressureless sintering
Journal name Materials Science and Engineering A   Check publisher's open access policy
ISSN 0921-5093
Publication date 2013-07
Sub-type Article (original research)
DOI 10.1016/j.msea.2013.03.023
Volume 574
Start page 176
End page 185
Total pages 10
Place of publication Lausanne, Switzerland
Publisher Elsevier
Collection year 2014
Language eng
Formatted abstract
An addition of 1.5at% Co to Ti-48Al-2Cr-2Nb (in at%) transformed the alloy from essentially unsinterable to fully sinterable at 1300°C. This, together with a simple powder coating process developed recently, has allowed near-net shape fabrication of the alloy for the first time by cold compaction and pressureless sintering. The addition of Co results in the formation of an intermediate face centred cubic (fcc) CoAl2Ti phase prior to 1220°C during heating. It subsequently reacts with an α phase leading to the formation of a Co-containing, wettable sintering liquid through a two-step process, CoAl2Ti+α→Liquid at 1256.2°C and CoAl2Ti+α→γ-TiAl+Liquid at 1267.2°C, and therefore full densification of the alloy. Without Co, sintering of the Ti-48Al-2Cr-2Nb alloy powder at 1300°C is controlled by the slow self-diffusion of Ti and interdiffusion of Ti and Al according to the activation energy determined. Transmission electron microscopy (TEM) identified an fcc CoAl2Ti phase and a hexagonal close packed (hcp) Co-enriched Ti(Al, Co, Cr, Nb) phase in the final as-sintered Ti-48Al-2Cr-2Nb-1.5Co alloy. They both form during cooling at 1240°C through Liquid+α→CoAl2Ti+Ti (Al, Co, Cr, Nb). The tensile and compressive properties of the as-sintered Ti-48Al-2Cr-2Nb-1.5Co alloy were compared to the original General Electric (GE) Ti-48Al-2Cr-2Nb alloy fabricated by casting or metal injection moulding.
Keyword Titanium aluminide
Mechanical properties
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Mechanical & Mining Engineering Publications
Official 2014 Collection
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Citation counts: TR Web of Science Citation Count  Cited 2 times in Thomson Reuters Web of Science Article | Citations
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