Laser-assisted processing of Ni-Al-Co-Ti under high pressure

• Published in: Materials and manufacturing processes 2017-10, Vol.32 (14), p.1606-1611
• Main Authors: Raju, Selva Vennila, Hrubiak, Rostislav, Drozd, Vadym, Saxena, Surendra
• Format: Article
• Language: English
• Subjects: Microstructure; modulus; strength; structures; superalloys; temperature; thermodynamics; XRD
• ISSN: 1042-6914; 1532-2475
• DOI: 10.1080/10426914.2016.1269913

Laser-assisted processing and in-situ characterization of a Ni 0.7 -Al 0.1235 -Co 0.15 -Ti 0.0265 alloy were carried out under a range of simultaneous hydrostatic high pressures of ∼30 GPa and high temperature conditions ∼2000°C using a laser-assisted heating in diamond anvil cell with synchrotron X-ray micro-diffraction. The characterization of the microstructure and X-ray diffraction analysis at ambient conditions confirmed the formation of the cuboids of ordered γ′ phase in the disordered γ matrix. The isothermal bulk modulus (B 0 ) and its first-order derivative (B 0 ') of the alloy were determined to be B 0  = 123 ± 9 GPa and B 0 ' = 5.7 ± 2.8. The in-situ characterization of the alloy at high temperatures under high pressures revealed that the γ′ phase transforms into the tetragonaly distorted D0 22 -type structure. This transformation is similar to the transformation that occurs in the ordered Ni 3 Al, responsible for the improved strength at high temperatures. High pressure was found to increase the onset temperature of the structural distortion. The pressure-temperature phase diagram of the Ni 0.7 -Al 0.1235 -Co 0.15 -Ti 0.0265 up to ∼30 GPa and ∼2000°C was determined and is reported here.