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Abstract

The formation of complex phases in metal alloys can significantly influence the macroscopic properties of the material. Topologically close-packed (TCP) phases in Ni-based superalloys, e.g., are brittle and their formation depletes the matrix of refractory elements which leads to a degradation of mechanical properties. The precipitation of Laves phases in steels, on the other hand, improves the strength of the material through precipitation hardening, whereas the formation of σ-phase precipitates has negative effects.

The atomic structure of complex phases is described by an ordered arrangement of coordination polyhedra around inequivalent lattice sites. To identify the corresponding TCP phases during atomistic simulations we have developed a polyhedron analysis. Of particular importance in trying to understand the formation and growth of TCP phases on an atomistic level are processes taking place at the interface between the complex phase and the alloy matrix. Here, we employ an adaptive kinetic Monte Carlo approach together with our polyhedron analysis to investigate concerted atomic rearrangements at the interface.