Fe-Al-Cr-Ti合金の耐酸化性と機械的性質におよぼすSi添加の影響

抄録

The oxidation resistance of Fe-Al(7%)-Cr(10%)-Ti(0.5%) alloys containing 0∼0.59% of silicon, in carbon dioxide gas at the temperature of 600∼900°C under a pressure of 10 kg/cm² were studied together with mechanical properties and workability.
The results obtained were summarized as follows:
(1) The oxidation of Fe-Al-Cr-Ti alloy in carbon dioxide gas decreased with increasing silicon content in the alloy. The addition of titanium to Fe-Al-Cr alloy for the purpose of improving the poor mechanical property of the alloy made the alloy less resistant to oxidation. The addition of silicon, together with titanium, brought about the recovery of good oxidation resistance of the Fe-Al-Cr alloy.
(2) Although the existance of silicon in the oxide film formed at 600°C was detected by X-ray microanalysis, SiO₂ could not be found by electron diffraction analysis of the film. These result showed that SiO₂ was existed in the layer as solid solution or in the film as amorphous state.
(3) At the testing temperatures higher than 700°C, silicon was not detected in any of the oxide films. The accelerated formation of Al₂O₃ on the surface of the alloy caused by alloying with silicon may be thought to have contributed to the increased oxidation resistance of the alloy.
(4) The tensile strength of the alloy at room temperature increased and the elongation decreased as its silicon content increased.
(5) The tensile strength and creep rupture strength of the alloys at high temperature increased with increasing content of silicon.