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arXiv · 2401.13954

Effect of chemical short-range order and percolation on passivation in binary alloys

Abhinav Roy·Karl Sieradzki·James M. Rondinelli·Ian D. McCue
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Abstract

We develop a percolation model for face centered cubic binary alloys with chemical short-range order (SRO) to account for chemical ordering/clustering that occurs in nominally random solid solutions. We employ a lattice generation scheme that directly utilizes the first nearest neighbor Warren-Cowley SRO parameter to generate the lattice. We quantify the effects of SRO on the first nearest neighbor three-dimensional (3D) site percolation threshold using the large cell Monte Carlo renormalization group method and find that the 3D site percolation threshold is a function of the SRO parameter. We analyze the effects of SRO on the distribution of the total number of distinct clusters in the percolated structures and find that short-ranged clustering promotes the formation of a dominant spanning cluster. Furthermore, we find that the scaling exponents of percolation are independent of SRO. We also examine the effects of SRO on the 2D-3D percolation crossover and find that the thickness of the thin film for percolation crossover is a function of the SRO parameter. We combine these results to develop a percolation crossover model to understand the electrochemical passivation behavior in binary alloys. The percolation crossover model provides a theoretical framework to understand the critical composition of passivating elements for protective oxide formation. With this model, we show that SRO can be used as a processing parameter to improve corrosion resistance.

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Abhinav Roy, Karl Sieradzki, James M. Rondinelli, Ian D. McCue. 2024-01-25. Effect of chemical short-range order and percolation on passivation in binary alloys. https://doi.org/10.1103/physrevb.110.085420

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