Ni基単結晶超合金TMS-238の耐酸化性とクリープ強度に及ぼす不純物元素Sbの影響

抄録

The influence of impurity element Sb on the oxidation resistance and creep strength of the single crystal superalloy TMS-238 was studied in this work. It was found that 1.1 ppm Sb clearly degrades the oxidation resistance, but not for the creep strength. As we increased the amount of Sb up to 3.8 ppm, the weight loss of the sample increased, as expected for the effect of Sb on the oxidation resistance. To understand the mechanism, the oxide structure was characterized by scanning electron microscope with energy dispersive X-ray spectroscopy (SEM-EDS), and three-dimensional atom probe (3DAP) was used to visualize the Sb distribution. 3DAP analysis has revealed Sb segregation of 0.03 at％ to 0.04 at％ at the oxide/substrate interfaces for 3.8 ppm Sb sample. These results indicated that the segregation of Sb, a low melting point metallic impurity, at the oxide/substrate interface degrades the oxidation resistance for TMS-238.

Fig. 6　(a) Typical 3DAP mass-to-charge-state ratio spectra at the Al₂O₃-substrate interface, and (b) magnified spectra for 3.8ppmSb sample.