Creep behavior and deformation mechanisms of precipitation-strengthened Ta-Mo-Cr-Ti-Al alloys

Motivation

Refractory high-entropy alloys (RHEA) and refractory complex concentrated alloys (RCCA) consisting of high melting point elements as well as passivating and light elements are promising new alloy groups which have shown excellent high temperature properties (e.g. high strength and resistance to oxidation). However, systematic investigation of creep resistance that is one of the most important requirements for structural materials application is scarce.

The two-phase microstructure of currently applied Ni-based superalloys provides excellent creep resistance at high temperature for gas turbine applications. Unfortunately, their limited solidus/solvus temperatures restrict the service temperature. Promisingly, some of the RCCA with high solidus temperatures have shown analogous two-phase microstructures, though different in the constituting phases. Therefore, it is necessary to study the creep deformation mechanisms of RCCA in these microstructural conditions.

Objectives

• Ta-Mo-Cr-Ti-Al alloys with two different Al contents
• Appropriate heat treatments are used to obtain the two-phase microstructure
• Assessment of high temperature creep resistance by means of reproducible characteristic values
• Understanding the creep deformation behavior and precipitation-strengthening mechanisms of the RCCAs

Investigations

• Evaluating alloy quality by O/N analysis to investigate material purity and identifing alloy composition precisely by chemical analyses
• Determining creep properties by varying temperature and stress for the creep tests
• Investigating microstructure after heat treatments and creep deformation by means of microscopic characterization (e.g. SEM, TEM, APT)

Funding

Chinese Scholarship Council