Statistical analysis of composition fluctuations and short-range order in stoichiometric Ni-Cr-Mo alloys

In the solution treated state Ni-Cr-Mo based alloys exhibit short-range order characterized by the appearance of diffuse intensity spots in electron diffraction patterns at {1120} positions. This short-range order appears due to of the formation of chemical heterogeneities. In the present work we report on the investigation of short-range order in Ni-33 at% Cr and Ni-16.7 at% Cr-16.7 at% Mo alloys using transmission electron microscopy. Chemical heterogeneities and their sizes are analyzed by statistical methods applied to three-dimensional atom probe data obtained on the same alloys. The obtained chemical heterogeneities are correlated to regions of short-range order in Ni-33 at% Cr and Ni-16.7 at% Cr-16.7 at% Mo alloys.