- By:
- Lim, Bryan ; Fancher, Christopher M; Boebinger, Matthew G; Poplawsky, Jonathan D; Proffen, Thomas E; Nandwana, Peeyush
- Journal Name:
- Journal of Alloys and Compounds
- Page Number:
- 186607
- Volume:
- 1056
- Publication Date:
- February 13, 2026
- View DOI Listing:
- https://doi.org/10.1016/j.jallcom.2026.186607
Abstract
Chromium (Cr) alloys combine low density with high-temperature strength but suffer from brittleness and rapid softening. Body-centered orthorhombic (BCO) CrNi2 laths have been shown to improve Cr-alloy high-temperature strength retention, yet their thermal stability and transformation behavior remain unclear. CrNi2 conventionally forms through long-range ordering from a face-centered cubic (FCC) phase. Using multiscale microscopy and neutron diffraction, we show that CrNi2 instead nucleates from a body-centered cubic (BCC) matrix, in a binary Cr85Ni15 alloy. Despite aging above the equilibrium ordering temperature, CrNi2 persists for ∼220 h at 760 °C before fully disordering, indicating sluggish transformation kinetics. The formation and decomposition follow differing transformation pathways (BCC → CrNi2 → FCC), revealing kinetic asymmetry not captured by equilibrium Cr-Ni phase diagrams. These findings redefine the transformation behavior of CrNi2, establish its metastable kinetic window, and suggest alloying strategies to stabilize CrNi2 for precipitation strengthening of high-temperature Cr-alloys.
