Intermetallic compounds of iron aluminides have attracted a lot of interest in recent decades as a replacement for high-alloy steels and superalloys due to their high specific strength and good oxidation and corrosion resistance, leading to improved performance of high-temperature components in energy, aerospace, and automotive applications. A scientific objective of this study is to exploit the unique characteristics of the laser-powder bed fusion (L-PBF) additive manufacturing (AM) process to improve the high-temperature creep performance of aluminides further and extend their application window to a higher temperature (> 750 ºC) for higher-performance rotational applications in aero-engines. Improved high-temperature strength can be achieved by precipitation hardening of FeAlTa iron aluminides through incoherent Laves phases.

The L-PBF samples’ microstructure typically consists of large columnar grains elongated along the vertical build direction by epitaxial solidification and several porosities. Therefore, it is expected that the components produced by L-PBF do not reach the structural integrity and mechanical properties of forged parts. In this context, a hybrid processing route consisting of L-PBF and hot forging could consolidate powder materials into near-net-shape forgings with refined microstructure and improved hot deformability. The advantage of hot-forming as a post-processing treatment is twofold: the closure of residual porosity and the refinement of the microstructure through dynamic recrystallization (DRX).

To investigate the deformation behavior of aluminide AM preforms, laboratory-scale isothermal compression tests with variable deformation rates between 10-3 s -1 and 1 s-1 are performed in a temperature range from 900 °C to 1100 °C up to a true strain of 0.8. The microstructure of the deformed specimens will be investigated by SEM – EBSD, and the primary deformation and restoration mechanisms will be identified. Special attention is given to a deeper understanding of DRX by specifying the critical conditions for DRX onset. The dependence of the recrystallized fraction on temperature, strain, and strain rate will be identified using the Johnson–Mehl– Avrami–Kolmogorov (JMAK) DRX kinetics model. The work hardening behavior of the samples under different deformation conditions will be studied using Kocks–Mecking plots.

Kinetic analysis of the flow behavior is performed using a hyperbolic sinusoidal function proposed by Sellars and Tegart. The apparent activation energy (Q) of hot deformation will be calculated, and the dependence of the peak stress values on the Zener-Hollomon parameter (Z) will be determined. The constitutive equations will be derived to describe the flow behavior of the material at elevated temperatures. The correlation between the critical, peak, and steady-state stress and strain values with a dimensionless Z/A parameter will be determined. Hot workability will be evaluated using the concept of a processing map based on the principles of the dynamic material model (DMM). The DMM will be used as a process design tool to identify the deformation mechanisms and optimal processing windows for producing defect-free parts in industrial-scale manufacturing.