In a breakthrough that could redefine the boundaries of additive manufacturing, researchers have unlocked the secret to creating crack-free bimetallic structures combining copper alloys and nickel-based superalloys. This advancement, led by Liyi Wang from the University of Pittsburgh’s Physical Metallurgy and Materials Design Laboratory, opens doors to more robust and reliable components for extreme environments, such as those found in rocket engine nozzles and other high-stakes energy sector applications.
The challenge of integrating copper alloys with Ni-based superalloys has long been hampered by interface cracking, a result of mismatched thermophysical properties. Wang and his team tackled this issue head-on, employing a sophisticated CALPHAD-based ICME framework. CALPHAD, which stands for Calculation of Phase Diagrams, combined with ICME, or Integrated Computational Materials Engineering, allowed the researchers to delve into nonequilibrium solidification and phase stability. Their goal? To predict and mitigate cracking susceptibility.
“What we found was fascinating,” Wang explains. “Liquid phase separation emerged as the dominant mechanism, altering solute redistribution and thermal stress accumulation. This was a factor that had been largely overlooked in bimetallic systems.”
The team’s experiments using wire arc additive manufacturing (WAAM) validated their model predictions. They discovered that crack-free interfaces between copper C18150 and Inconel 625 could be achieved with intermediate layers containing 65% Inconel 625 by weight. This composition significantly reduced cracking susceptibility, as measured by the cracking susceptibility coefficient (CSC).
The implications for the energy sector are substantial. “By establishing a quantitative correlation between phase separation and CSC, we’ve laid the groundwork for analyzing and designing systems with similar microstructural features,” Wang notes. This research, published in the journal *Science and Technology of Advanced Materials* (translated to English as *Science and Technology of Advanced Materials*), offers new principles for designing defect-resistant bimetallic components.
The commercial impact of this research could be profound. In industries where extreme environments are the norm—such as aerospace, energy generation, and chemical processing—the ability to create reliable, crack-free bimetallic structures could lead to more efficient and durable components. This could translate to cost savings, improved performance, and enhanced safety.
As the energy sector continues to push the limits of technology, innovations like this one will be crucial. By bridging the gap between computational modeling and practical application, Wang and his team have not only advanced the field of additive manufacturing but also paved the way for future developments in materials science.
“This work is a testament to the power of integrating computational tools with experimental validation,” Wang concludes. “It’s a step forward in our quest to design materials that can withstand the most demanding conditions.”