Planar fault energies in superalloys from first principles
July 17-21, 2016
Planar fault energies in superalloys are largely responsible for the complex deformation processes observed. In the gamma phase, the intrinsic and extrinsic stacking fault energies are thought to be responsible for controlling how easily dislocations climb around the gamma prime precipitates. In the gamma prime phase, the various planar fault energies (superlattice intrinsic and extrinsic stacking faults, complex intrinsic and extrinsic stacking faults and anti-phase boundaries on the 111 and 001 planes) control the operating shearing modes that allow dislocations or ribbons of dislocations to cut through precipitates. Whereas the effect of composition on the planar fault energies of the gamma phase are well understood, the same cannot be said of planar fault energies of the gamma prime phase. In this presentation, we will explore the effect of compositional variations on some of these planar fault energies, investigating how solute atoms change these energies on both sides of perfect stoichiometry (A3B). We will look at all transition metals, to highlight trends across the periodic table, and discuss the effects of temperature on planar fault energies. Our results show clear trends across the periodic table, indicating that gamma prime ‘stabilisers' are also responsible for increasing the planar fault energies of gamma prime phase. Similar to the gamma phase, these effects appear to be primarily due to electronic structure effects rather than size effects.
Alessandro Mottura, Joshua Allen, and Abed Al Hasan Breidi, "Planar fault energies in superalloys from first principles" in "Beyond Nickel-Based Superalloys II", Chair: Dr Howard J. Stone, University of Cambridge, United Kingdom Co-Chairs: Prof Bernard P. Bewlay, General Electric Global Research, USA Prof Lesley A. Cornish, University of the Witwatersrand, South Africa Eds, ECI Symposium Series, (2016). http://dc.engconfintl.org/superalloys_ii/16