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

ABSTRACTLaser-assisted processing and in-situ characterization of a Ni0.7-Al0.1235-Co0.15-Ti0.0265 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 (B0) and its first-order derivative (B0’) of the alloy were determined to be B0 = 123 ± 9 GPa and B0’ = 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 D022-type structure. This transformation is similar to the transformation that occurs in the ordered Ni3Al, responsible for the improved strength at high temperatures. High pressure was found to increase the onset te...