  Solute segregation is used to limit grain growth in nanocrystalline metals,
but this stabilization often breaks down at high temperatures. Amorphous
intergranular films can form in certain alloys at sufficiently high
temperatures, providing a possible alternative route to lower grain boundary
energy and therefore limit grain growth. In this study, nanocrystalline Ni-W
that is annealed at temperatures of 1000 {\deg}C and above, then rapidly
quenched, is found to contain amorphous intergranular films. These complexions
lead to a new, unexpected region of nanocrystalline stability at elevated
temperatures.
