Phase equilibria of the AlCoW system at 600 °C

Phase relationship in the ternary AlCoW system was established for the whole composition range at 600 °C by X-ray powder diffraction, scanning electron microscopy and energy dispersive spectroscopy. Isothermal section of this system comprises of 15 three-phase and 28 two-phase regions. Except the L12-γ′ phase, a new ternary phase T has been found. The average composition of the T phase is 22.6 at.% Al, 67.0 at.% Co and W in balance. The solubility of W in AlCo is 3.0 at%, the solubility of Al in Co3W and Co7W6 is both 3.1 at%, and the solubility of Co in Al4W reaches 3.6 at.%. Solubility of the third component in the other binary phases is limited. The present work is essential to develop a thermodynamic database for Co-related high-temperature alloy design.