Unveiling the Re effect in Ni-based single crystal superalloys

Area of Science:

• Materials Science
• Metallurgy
• Mechanical Engineering

Background:

• Single crystal nickel-based superalloys are vital for high-temperature applications like gas turbines.
• The addition of Rhenium (Re) dramatically improved creep lifetime, but the underlying mechanisms were unclear.

Purpose of the Study:

• To elucidate the controversial "Re effect" mechanism in single crystal nickel-based superalloys.
• To provide direct evidence of Rhenium's role in creep deformation.

Main Methods:

• Combined transmission electron microscopy (TEM) and atom probe tomography (APT).
• Phase field modeling was employed to simulate and understand deformation mechanisms.

Main Results:

• Direct evidence of Rhenium (Re) enrichment at crystalline defects, specifically partial dislocations, formed during creep.
• Rhenium enrichment was shown to impose a drag effect on dislocation movement.
• This drag effect leads to reduced creep strain rates and enhanced creep properties.

Conclusions:

• The "Re effect" is attributed to Rhenium's segregation to partial dislocations, hindering their motion.
• These findings offer crucial insights for designing advanced superalloys.
• Improved superalloys are key to reducing CO2 emissions in aviation.