SOURCE: AFI
Researchers from the Indian Institutes of Technology (IIT Madras, IIT Jodhpur, IIT Hyderabad, and IISc Bangalore), in collaboration with the Indian Space Research Organisation (ISRO) and the Defence Research and Development Organisation (DRDO), have achieved a significant breakthrough in materials science. The team has dramatically improved the creep resistance of 3D-printed Inconel 718 (IN718), a nickel-based superalloy critical for rocket engines and jet turbines. Announced on May 7, 2025, this development addresses a long-standing challenge in additive manufacturing, paving the way for more reliable aerospace components.
Inconel 718 is a high-performance superalloy widely used in aerospace for its excellent strength, corrosion resistance, and ability to withstand extreme temperatures. In its traditional wrought form, IN718 performs reliably in demanding applications like ISRO’s rocket engines and IAF jet turbines. However, the 3D-printed (additive-manufactured) version has struggled to match this performance at high temperatures—a critical requirement for aerospace use.
The issue lies in the rapid solidification process inherent to additive manufacturing. During 3D printing, the material cools quickly, causing Niobium (Nb)—a key alloying element in IN718—to segregate at grain boundaries. This segregation leads to the formation of precipitate-free zones (PFZs), which are soft spots in the microstructure. Over time, these PFZs become failure points under high-temperature creep conditions, where materials deform slowly under constant stress, drastically reducing the component’s lifespan.
The collaborative team, comprising experts from @iitmadras, @iitjodhpur, @iiscbangalore, @IITHyderabad, @isro, and @DRDO_India, tackled this challenge using advanced microstructural analysis. They employed techniques like scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) to study the alloy’s behavior at the atomic level. Their findings revealed that the key to mitigating PFZs lay in optimizing the post-processing heat treatment.
By raising the solution treatment temperature to 1150°C—higher than the conventional 980-1050°C typically used for IN718—the researchers enhanced the diffusion of Niobium. This higher temperature allowed Nb to distribute more uniformly throughout the microstructure, effectively eliminating PFZs. The treatment also promoted the formation of strengthening precipitates like gamma-prime (??) and gamma-double-prime (??), which are critical for maintaining the alloy’s strength at elevated temperatures.
The results were striking. The modified heat treatment process led to a fivefold increase in the creep rupture life of 3D-printed IN718, bringing its performance much closer to that of its wrought counterpart. Creep rupture life—the time a material can withstand constant stress at high temperatures before failing—is a key metric for aerospace components like turbine blades and rocket engine nozzles, which operate under extreme conditions.
This breakthrough has significant implications for India’s aerospace sector. ISRO, which relies on IN718 for components in engines like the CE-20 cryogenic engine used in the GSLV Mk III, can now explore additive manufacturing for faster, cost-effective production without sacrificing reliability. Similarly, DRDO’s projects, such as the Kaveri engine for fighter jets, could benefit from lighter, more complex 3D-printed parts that maintain structural integrity at high temperatures.
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