ICAMS / Interdisciplinary Centre for Advanced Materials Simulation
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Understanding the effects of stress orientation - propagation of superlattice stacking faults in Ni-based superalloys

Date: 26.11.2020
Time: 12:00
Place: Online event

Fernando León-Cázares, University of Cambridge, Cambridge, United Kingdom

Plasticity in metals is heavily influenced by the stress orientation, but studying its effects on multiple deformation mechanisms is often cumbersome. There is effectively very little to do other than tabulating the Schmid factors of all the relevant slip systems. To address this, a novel orientation analysis framework for face-centred crystals is introduced, and its applicability is highlighted with the use of new "stress orientation maps", graphical tools to simultaneously scrutinise the stress states of all <110> and <112> slip systems in a comprehensive, yet intuitive way. This framework is then applied to build a theory of superlattice stacking fault propagation during creep in Ni-based superalloys. Whilst these faults have been studied for over four decades, this work is the first one to derive the equations for the criteria behind the appearance of all their configurations. Agreement with experimental results is then obtained for single crystal data from the literature and a quantitative analysis of the faults developed in a crept polycrystalline alloy.

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