Analysis of nano-scaled composition fluctuations as observed by 3-dimensional atom probing of alloys

A new statistical method allows to quantify nano-scaled concentration fluct uations observed in alloys by 3-dimensional atom probing. This method invol ves systematic reduction of stochastic concentration fluctuations in the ex perimental data by a wavelength dependent filtering (WDF). Comparing the re sulting variance of the concentration values with that of the appropriate s tatistically random counterpart uncovers wavelength and concentration ampli tude of nonrandom concentration fluctuations. The advantage of the WDF is d emonstrated by the analysis of the melt-spun amorphous Fe-14B alloy for whi ch a concentration fluctuation with an average wavelength of 2 nm and an am plitude of 7 at.% B was evaluated from 3-dimensional atom probe data.