Sintering Titanium Aluminides with Co Addition

Abstract:

Co additions to titanium aluminides were assessed to decrease the typically high sintering temperatures necessary for the densification of intermetallics. Compositions based on the binary Ti-45Al with ternary Co variations between 1-10 at.% were investigated. The specimens were cylinders with 8 mm diameter prepared using blended elemental powders followed by cold uniaxial pressing. Sintering was carried out under an argon atmosphere at different temperatures ranging from 1100 to 1400 °C for 2 hours in a tube furnace. The results indicated that there was a systematic increase in densification with Co additions. The relative density of the reference material Ti-45Al was approximately 53%, however, Co addition of 10% led to densifications in the order of 80%. A strong effect of decreasing the sintering temperature was achieved with Co additions. The microstructure changed from fully lamellar with 1 at.% Co sintered at 1400 °C to duplex with higher Co additions sintered at 1200 °C. Besides the γ-TiAl and α₂-Ti₃Al equilibrium phases, the formation of a CoAl₂Ti intermetallic was identified. The addition of 7% Co led to the highest hardness of approximately 450 HV.

• Periodical: Materials Science Forum (Volume 1146)
• Pages: 13-19
• DOI: https://doi.org/10.4028/p-H9wNaT
• Online since: March 2025
• Authors: Lorenzo Quaglio, Warlen Alves Monfardini, Juliano Soyama*
• Keywords: Co Addition, Sintering, Titanium Aluminides

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