Effect of rhenium addition on the microstructure of the superalloy Inconel 706

Alloying of single-crystal superalloys by Re (CMSX4, CMSX10, RR3000, etc.) decreases the coarsening rate of γ′ precipitates. In order to clarify whether this effect works in the superalloy Inconel 706, its composition has been modified by adding about 2 wt.% Re. Microstructure and composition of the modified Inconel 706 superalloy are investigated by means of transmission electron microscopy (TEM) and three-dimensional atom probe (3DAP) after long-term exposure at 750 °C. 3DAP measurements reveal the partitioning behavior of Re to the matrix in the 706 superalloy. It is found that the stability of γ′ and γ″ precipitates is not significantly affected by the Re addition. The possible reasons for this only weak Re effect on the superalloy Inconel 706 are discussed.