Institute for Applied Materials – Materials Science and Engineering

Novel eutectic and high-melting-point Mo-Si-Ti alloys manufactured by Additive Manufacturing: microstructure, texture, and induced properties

Dr.-Ing. Daniel Schliephake

Motivation

Mo-based silicides are under research for over 20 years now. They show excellent mechanical properties at high temperatures and are therefore reckoned as potential high-temperature material to operate above 1200°C. By adding Boron, not only the mechanical properties tend to improve, further, the oxidation resistance increases as well.

However, a considerable disadvantage is the so-called „pesting“ phenomena, which is typical for refractory metals. The formation of volatile oxides can cause a disintegration of the component at intermediate temperatures. Recently, eutectic and near-eutectic Mo-Si-Ti alloys have shown to resist this pesting phenomenon fort the first time.

Furthermore, the well-known ductile-to-brittle transition temperature makes it difficult to manufacture and process Mo-based silicides. Nevertheless, using Additive manufacturing techniques like electron beam melting with its high pre-heating temperatures might enable us to build complex net-shaped components of this alloy system.

Objectives

  • Identifying of appropriate Mo-Si-Ti alloys (in collaboration with M.Sc. Susanne Obert)
  • Developing of process parameters to build near pore- and crack-free parts
  • Correlating process parameters with microstructure and texture of Mo-Si-Ti alloys
  • Characterization of mechanical properties (up to 1200°C)
  • Characterization of oxidation resistance under pesting and later application temperature
  • Correlation between process parameters, microstructure, and properties

Investigations

  • parameter study to build nearly dense components
  • microstructure characterization and microstructural stability at high temperatures
  • chemical analysis of elements and impurities to judge the processing route
  • determining mechanical properties under bending, compression and tension load