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CAVS Studies High Temperature Aerospace Materials in Modern Turbine Engines

December 6, 2013

The Center for Advanced Vehicular Systems (CAVS) at Mississippi State University recently received multi-year funding from the Multi-Scale Structural Mechanics and Prognosis program (PM: Dr. David Stargel) in the Air Force Office of Scientific Research (AFOSR) to better understand how to engineer the materials used in the hot section of turbine engines of modern civilian and military aircraft.  These high temperature materials - single crystal nickel-based superalloys, which are primarily composed of nickel and aluminum with a number of other elements in smaller concentrations - possess a very unique microstructure that enables them to operate at high temperatures while retaining a high level of strength, high-temperature creep resistance and fatigue life.  In fact, the efficiency and power of these turbine engines is intimately tied to the maximum achievable operation temperature of these nickel-base superalloys.

The AFOSR research project titled "Hierarchically-driven approach for quantifying materials uncertainty in creep deformation and failure of aerospace materials" is being led by Dr. Mark Tschopp, a research faculty at Mississippi State.  Dr. Tschopp works in the computational manufacturing and design group at the Center for Advanced Vehicular Systems, a major unit of the university's Bagley College of Engineering.  For the last year, Dr. Tschopp has also held a position at the U.S. Army Research Laboratory in Aberdeen Proving Ground, MD.

The research uses a combination of critical high temperature experiments and computational studies to better understand the role that the microstructure plays in these superalloys.  The microstructure is determined by the manufacturing process, which is extremely challenging as the turbine blades are produced in as a single crystal and have extremely thin walls and complex cooling passages to help cool the blade in the hot section of the turbine engine.  Therefore, understanding how microstructure changes with processing and how properties change with microstructure is critical to predicting and extending the life of these components.

Some of their initial findings recently were published as an "Editor's Choice" article in Metallurgical Transactions A, a premier peer-reviewed journal for research in physical metallurgy and materials science.  As the superalloy solidifies, dendrites grow within the solidifying liquid metal.  This first work details different computational methods for characterizing these dendritic microstructures, which can ultimately help determine important mechanical properties of these materials at high temperatures (2000 F).

Tschopp's research colleagues include Dr. Andrew Oppedal, a Postdoctoral Associate at CAVS; Dr. Kiran Solanki of Arizona State University's School for Engineering Matter, Transport and Energy; Dr. Jon Miller and Dr. Andrew Rosenberger of the Air Force Research Laboratory; and Dr. Kris Darling of the U.S. Army Research Laboratory.

Research on the program now is ongoing, with collaborators at the Air Force Research Laboratory providing their unique experimental research capabilities and expertise to help this fundamental research project into the high temperature creep behavior of these single crystal nickel-based superalloys.  Arizona State University and the Army Research Laboratory are providing experiments at small scales to sample the change in strength within these complex microstructures.  Mississippi State's CAVS is utilizing the principles of integrated computational materials engineering (ICME) to combine material characterization, computational analysis, failure analysis, and vital research information from collaborators to help understand how to better engineer and predict properties in these materials.

"Materials design and engineering requires very large multi-faceted efforts grounded in both computational and experimental research.  The goal of this fundamental research project is to tackle one missing piece of the puzzle that may impact future predictive models for this important class of materials," Dr. Tschopp said.

For more information, contact Dr. Tschopp at 410-306-0855 or mtschopp@cavs.msstate.edu.

Article website: http://dx.doi.org/10.1007/s11661-013-1985-3