Věra Vodičková

The Effect of Low Concentrations Nb and C on the Structure and High-Temperature Strength of Fe3Al Aluminide

The Fe3Al iron aluminide alloyed by low concentrations of Nb and C (cNb, cC) is studied. The influence of the cNb/cC ratio on the structure and high-temperature yield strength of iron aluminide was investigated. The structure and phase composition were studied by scanning electron microscope equipped with EDS and EBSD. The strengthening mechanisms are detected as strengthening by incoherent precipitates of NbC and as a solid solution hardening by Nb atoms.

The Effect of Laves Phase (Fe,Al)2Zr on the High-Temperature Strength of Carbon-Alloyed Fe3Al Aluminide

The effects of carbon on the phase structure and on the yield stress σ0.2 in the temperature range from 873 K to 1073 K (600 °C to 800 °C) of the Fe3Al type aluminides alloyed by Zr are analyzed. Four alloys with Zr and C in ranging from 1.0 to 5.0 at. pct of additives were used. The appearing of either Laves phase (Fe,Al)2Zr and/or carbides depend on the difference in concentrations, cZr − cC. This parameter (cZr − cC) has been selected instead of the concentration ratio cZr/cC used in previous works since it exhibits a significantly better correlation with the Laves phase concentration which influences the high-temperature yield stress, σ0.2, of the tested alloys. The presence of Laves phase or eutectic (matrix—Laves phase), respectively, enhances the value of the yield stress σ0.2. The amount of Laves phase is decreased by the presence of C due to the affinity of carbon to Zr.