Deformation behaviour of a cast Fe–19Al–5Cr-0.04Zr alloy at room and intermediate temperatures

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2023-10, Vol.885, p.145580, Article 145580
• Main Authors: Kollmannsberger, Eva, Stangl, Christoph, Pütz, René Daniel, Zander, Daniela, Saage, Holger
• Format: Article
• Language: English
• Subjects: Fatigue; Iron aluminides; Mechanical properties; Recovery effects; Strain hardening rate; Twinning
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2023.145580

The mechanical properties of a Fe–19Al (at.%) alloy containing 5 at.% Cr as the main alloying element are presented and discussed. While the alloy behaves brittle at room temperature and 100 °C, tensile stress-strain curves at temperatures between 200 °C and 500 °C show strain hardening recovery effects similarly to those of fcc twinning induced plasticity (TWIP) steels. It is supposed that a combination of dislocation glide and formation of internal boundaries in the submicron range leads to similar strain hardening stages at intermediate temperatures (200 °C–500 °C) in the FeAl alloy as usually observed in TWIP steels at room temperature. The maximum strain hardening rate after recovery reaches very high values of about G/19 at 400 °C. Low-cycle fatigue (LCF) tests at 400 °C and 500 °C up to strain amplitude values of 0.6% and stress-relaxation tests do not reveal high back stresses or pseudoelasticity in the FeAl alloy. This indicates that the deformation structures responsible for the strain hardening rate recovery remain stable upon stress relief. •The FeAl alloy reveals strain hardening recovery effects at moderate temperatures.•The formation of macro twins is observed at higher strain values.•Low cycle fatigue behaviour is comparable to that of P91 steel.•Bauschinger back stresses are lower than for P91 and TWIP steels.•The alloy shows high sensitivity of elongation at fracture to surface roughness.