Superalloys, extreme heat and tiny cracks: research for future aircraft engines
11 Jun 2026
How can you make aircraft engines more efficient? One way is to run them at higher temperatures, which improves fuel efficiency and lowers emissions. In his doctoral thesis at University West, researcher Achmad Ariaseta has studied two new superalloys designed to survive the extreme heat in future jet engines. He wanted to know: Can these advanced materials be welded without cracking?
Achmad Ariaseta has studied two new superalloys that may be of interest for future jet engines. Photo: University West.
Aeroengines made from Alloy 718 have been the industry standard for decades. However, these engines are limited to operating at temperatures below approximately 650 °C. To push beyond that limit and improve efficiency, new nickel-based superalloys have been developed, capable of handling temperatures closer to 750 °C.
"My research focuses on how these new superalloys behave during welding. First, we wanted to understand how likely they are to crack when welded. We then investigated the metallurgical factors responsible for the formation of microscopic cracks and, most importantly, how the likelihood of crack formation can be minimized by tailoring the alloys’ pre-weld microstructures", Achmad explains.
Looking inside the metal
In his thesis “Microstructural Analysis and Weld Hot Cracking Susceptibility of Next-Generation Nickel-Based Superalloys: VDM Alloy 780 and Alloy G27”, Achmad studied the new materials on an incredibly small scale. Advanced electron microscopes allowed him to study structures down to a single nanometre, close to the atomic level. At these scales, tiny grain boundaries can become weak points where cracks can begin to form.
"When you weld, you locally melt the material in the specific area called the heat-affected zone. That area becomes weaker because part of it turns into liquid. When that liquid along the grain boundary is exposed to thermal stresses during welding, cracks can form."
The research also included extensive weldability testing. Samples were repeatedly welded and stress tested to force cracks to appear and then analysed by measuring the length of all individual cracks.
“Boron is the bad guy”
One of the most surprising discoveries involved the element boron. Tiny amounts of boron are intentionally added to superalloys because they improve performance during engine operation. But during welding, the same element can suddenly become a problem. The reason is that boron atoms can segregate in specific microscopic regions called grain boundaries during welding. This changes how the metal solidifies and increases the risk of cracks forming.
"Boron is kind of a double-edged sword. From a welding perspective, boron can actually be problematic. When boron becomes locally concentrated in the grain boundary during welding, the temperature range between the liquidus and solidus during solidification of the grain boundary liquid becomes wider, which increases the susceptibility to cracking."
Finding a recipe for safer welding
Achmad found that this could be managed with a carefully controlled heat treatment. By adjusting temperature and heating time before welding, he was able to find the optimal microstructure resistant to cracking.
"We found a heat-treatment recipe with a specific temperature and holding time that makes the microstructure more resistant to cracking during welding. With regards to the VDM Alloy 780, it is really, really weldable. Even when the crystal or grain size was six times larger than in the widely used Alloy 718, it still produced fewer cracks."
Guidelines for the industry
Achmad’s research has resulted in practical heat-treatment guidelines for VDM Alloy 780 and G27 for the industry. This can also help aero engine manufacturers choose materials, welding methods, and welding parameters for future engine components made from the new superalloys, which is an important step towards more efficient and potentially more climate-friendly aviation.
"Companies like GKN Aerospace in Trollhättan, which has also been a valuable partner in my research, are interested in using these materials in future engine components."
Driven by curiosity
What drives Achmad as a researcher is curiosity itself. He likes to explore and solve problems.
"When something is still unexplained, it makes me want to understand it even more. The most fascinating part is when you finally find the link between a phenomenon and the real root cause behind it."
That process was especially challenging in his PhD project because the materials he studied were completely new. There was very little previous research to rely on.
"I couldn’t find much relevant literature. We had to figure things out ourselves."
Back to Indonesia
After more than five years in Trollhättan, Achmad is now preparing to return home to become an assistant professor at Bandung Institute of Technology in Indonesia. There, he also hopes to continue collaborating with his Swedish colleagues in Trollhättan.
Read Bassam Massouhs doctoral thesis: “Microstructural Analysis and Weld Hot Cracking Susceptibility of Next-Generation Nickel-Based Superalloys: VDM Alloy 780 and Alloy G27”
Contact: Achmad Ariaseta, PhD in Production Technology, University West: achmad.ariaseta@hv.se or ariaseta@itb.ac.id
At University West, we conduct research in collaboration with the surrounding world to create a better future.