Investigation of phase transformations by in-situ neutron diffraction in a Co–Re-based high temperature alloy

In-situ neutron diffraction at high temperatures was used to investigate phase transformation in a Co–Re-based alloy. Stability of carbides and transformation of Co matrix from ε (hcp) to γ (fcc) phase were studied. The ε ⇄ γ phase transformation exhibited a large hysteresis with temperature. The alloy has a complex microstructure with Cr23C6, TaC and σ phase stable over a wide temperature range. The hysteresis is the result of composition interplay between Co-matrix and other phases, e.g. Cr-carbide and σ. TaC is stable at high temperatures up to 1300 °C.