摘要
We have investigated the effect of Ti addition on the partitioning behavior of Si in Ni-19 at. pct Al-xSi-yTi alloys (x = 1.0 to 2.5 at. pct and y = 0.0 to 2.0 at. pct). The elemental partition ratios between the γ and γ′ phases were determined by electron probe microanalysis. The results indicate that an increase in the Ti content increases the partitioning tendency of Si in the γ matrix. However, Si was preferentially partitioned in the γ′ phase after 816 hours aging at 1373 K (1100 °C). Interestingly, a CALPHAD-based simulation also predicted the tendency of Si to partition in the γ phase with increasing Ti content. However, Si was predicted to preferentially partition in the γ matrix. First-principles calculations suggest that Ti atoms can replace Si atoms in the γ′ phase and reject Si atoms into the face-centered cubic γ matrix. Furthermore, the partitioning behavior of Si could also be influenced by the presence of point defects and the volume fraction of the γ′ phase.