Unveiling the Re effect in Ni-based single crystal superalloys

• Published in: Nature communications Vol. 11; no. 1; p. 389
• Main Authors: Wu, Xiaoxiang, Makineni, Surendra Kumar, Liebscher, Christian H., Dehm, Gerhard, Rezaei Mianroodi, Jaber, Shanthraj, Pratheek, Svendsen, Bob, Bürger, David, Eggeler, Gunther, Raabe, Dierk, Gault, Baptiste
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 20.01.2020; Nature Publishing Group; Nature Portfolio
• Subjects: 147/143; 639/301/1023/1026; 639/301/1023/303; Carbon dioxide; Carbon dioxide emissions; Creep strength; Crystal defects; Dislocations; Electric power generation; Enrichment; Gas turbine engines; Gas turbines; High temperature; Humanities and Social Sciences; Image resolution; Modelling; multidisciplinary; Nickel; Nickel base alloys; Oxidation; Oxidation resistance; Power plants; Rhenium; Science; Science (multidisciplinary); Single crystals; Strain rate; Superalloys; Thermal stability; Transmission electron microscopy
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-14062-9

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. 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. Here, we provide direct evidence of Re enrichment to crystalline defects formed during creep deformation, using combined transmission electron microscopy, atom probe tomography and phase field modelling. We reveal that Re enriches to partial dislocations and imposes a drag effect on dislocation movement, thus reducing the creep strain rate and thereby improving creep properties. These insights can guide design of better superalloys, a quest which is key to reducing CO 2 emissions in air-traffic. Adding minute amounts of rhenium to Ni-based single crystal superalloys extends their high temperature performance in engines, but the reasons behind that are still unclear. Here, the authors combine high resolution imaging and modelling to show that rhenium enriches and slows down partial dislocations to improve creep performance.