Institute for Applied Materials – Materials Science and Engineering

Development and Mechanical Characterization of Mo-Si-B-(Ti) for High Temperature Applications

M.Sc. Susanne Obert

Motivation

Currently, mechanically loaded turbine blades are made of single crystalline Ni-base superalloys (with surface temperatures of around 1100°C). Increase of efficiency is desirable because of ecological and economical reasons. For example, an increase of the combustion temperature is one option, but not suitable because of the low melting point of Ni-base superalloys (Tm ≈ 1400°C). Mo-Si-B alloys (Tm > 2000°C) offer the potential of overcoming the limitation in combustion temperature by good oxidation and creep resistance above 1200°C.

Goals

  • development of technically applicable, creep resistant Mo-Si-B-Ti alloys including oxidation resistant coating systems for a wide temperature range and humid atmosphere

  • analysis of oxidation mechanisms, long term oxidation behavior and mechanical properties of novel Mo-Si-B-Ti alloys

  • analysis of the protectiveness of the developed coating systems during creep loading

  • alloy synthesis and adjustment of desired microstructures by heat treatments

  • mechanical characterization at room temperature and elevated temperatures

Methods

  • analysis of microstructure and thermal stability
  • microstructural analysis and thermal stability at elevated temperatures
    evaluation of the alloys’ synthesis route by chemical composition

  • determination of brittle-to-ductile transition temperature and fracture toughness by applying 4-point-bending tests

  • determination of creep behavior under tensile load

  • determination of physical properties