Powder Synthesis and Fundamental Properties of Mo-Ti-Si Alloys for Additive Manufacturing and Development of Oxidation-Resistant Cr-Mo-Si Alloys
Motivation
The Research Training Group RTG2561 MatCom-ComMat (Materials Compounds from Composite Materials) deals with the development of composite materials for use at operating temperatures of more than 1300 °C and under extreme environmental conditions. It is a collaborative project between Researchers from KIT, Darmstadt University of Technology, and Dechema Forschungsinstitut. To achieve this, high melting point multi-phase materials based on refractory metal silicide systems will be prepared to serve as a substrate material to be coated with polymer-derived ceramic nanocomposites (PDC-NCs) based on Si(M)CX. Project number 8 is dedicated to the synthesis, processing and characterization of refractory metal silicide-based high-temperature alloys for use as substrate material of the new material composite within the framework of the RTG.
On the one hand, the powder metallurgical processing of a metallic/intermetallic alloy from the Mo-Si-Ti system is investigated to enable component fabrication by additive manufacturing. The alloy with composition Mo-20Si-52.8Ti (at.%) offers a promising property profile due to its excellent microstructure stability and creep performance at ultra-high temperatures and its excellent oxidation resistance.
On the other hand, the diversity of possible substrate materials is advanced by characterization of new alloys in the Cr-Mo-Si system. Special emphasis is placed on the oxidation resistance of new alloys above 800 °C. Fine-lamellar, two-phase microstructures similar to those of oxidation-resistant Mo-Si-Ti alloys are deliberately tuned on Cr-Mo-Si alloys. In cyclic oxidation tests, the alloys are repeatedly subjected to strong temperature fluctuations, simulating a loading case close to the application. Oxidation resistance is assessed by analyzing mass change and oxide layer growth.
Objectives
- Alloy synthesis via arc melting
- Metallographic sample preparation
- Heat treatments in protective atmospheres
- Cyclic oxidation in air
- Scanning electron microscopy based characterization of microstructures and oxide scales by means of back scattered electron contrast and energy dispersive X-Ray spectroscopy
- Phase identification via X-Ray diffraction
- O/N-Analysis via hot carrier gas extraction
Investigations
- Alloy synthesis by arc melting
- Metallographic preparation
- Heat treatements
- Cyclic oxidation
- Scanning electron microscopy studies of microstrcuture and oxide scales
- X-ray diffraction
- O/N analysis by carrier gas hot extraction
Funding
Graduate school 2561 "Materials Compounds from Composite Materials" by Deutsche Forschungsgemeinschaft
