AFRL-Funded Research Identifies New Material Properties

  • Published
  • By Air Force Office of Scientific Research
  • AFOSR
ARLINGTON, Va. --  AFRL-sponsored researchers from the Department of Materials Science and Engineering at the University of Wisconsin have identified new properties in molybdenum-silicon-boron (Mo-Si-B) alloys. The researchers discovered that the alloys exhibit melting temperatures more than 800°C higher than state-of-the-art nickel-based alloys, good oxidation and resistance, and useful mechanical properties. In order to provide the fundamental understanding needed for further development and application of Mo-Si-B alloys, the research focuses on basic studies of thermodynamic stability, diffusion kinetics, and microstructure control. Preliminary tests involving elevated-temperature mechanical properties have demonstrated that alloys based on this new microstructure are 50% stronger than current alloys, which are constrained by their melting temperatures.

By applying modern electronic structure computational analysis, in conjunction with considering atomic size factors and conducting critical experimental tests, the researchers are establishing guidelines for evaluating alloy phase stability and microstructure control. They have identified a key alloy phase that spans a wide range of compositions. They are also examining the atomic arrangements necessary for achieving novel compositions. To obtain accurate information regarding defect structure, the researchers are employing several structural and modeling analysis methods--one of which entails use of the Intense Pulsed Neutron Source at Argonne National Laboratories--to obtain neutron diffraction measurements.

Increases in aero-engine operating temperatures exceed the limits of the current, nickel-based superalloys; however, the higher-temperature environment equates to greater engine power and efficiency. Thus, the Mo-Si-B alloys' enhanced capacity for elevated-temperature operations is critical for future applications in hypersonic flight.