Unveiling the Re effect in Ni-based single crystal superalloys

Xiaoxing Wu, Surendra Kumar Makineni, Christian H Liebscher, Gerhard Dehm, Jaber Rezaei Mianroodi, Pratheek Shanthraj, Bob Svendsen, David Burger, Gunther Eggeler, Dierk Raabe, Baptiste Gault

Research output: Contribution to journalArticlepeer-review

Abstract

Single crystal Ni-based superalloys have long been an essential material for gas turbines in aero engines and power plants due to their outstanding high temperature creep, fatigue and oxidation resistance. Continuing efforts in alloy design led to improvement of their high temperature performance to enable higher operating temperature and hence better conversion efficiency and reduced fuel consumption. A turning point was the addition of only 3 wt.% Re in the second generation of single crystal Ni-based superalloys which almost doubled the creep lifetime. Despite the significance of this improvement, the mechanisms underlying the so-called “Re effect” have remained controversial. Since Re increases the mass density of the turbine and is a rare element, it is of great scientific and economic significance to understand the role of Re in extending the lifetime of single crystal Ni-based superalloys. Here, we provide direct evidence of Re segregating to crystalline defects formed during creep deformation, using combined transmission electron microscopy, atom probe tomography and phase field modelling. We reveal that Re segregates to partial dislocations and imposes a drag effect on dislocation movement, thus reducing the creep strain rate and thereby improving creep properties. These new insights can guide design of better superalloys, a quest which is key to reducing CO2 emissions in air-traffic.
Original languageEnglish
Article number389
Pages (from-to)389
JournalNature Communications
Volume11
Issue number1
Early online date20 Jan 2020
DOIs
Publication statusPublished - 20 Jan 2020

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