Effect of molybdenum on grain boundary segregation in Incoloy 901 superalloy

In this paper, the effect of molybdenum on the grain boundary segregation of other elements was studied in Incoloy 901 superalloy. Initially, five alloys were prepared with different percentages of Mo by using a vacuum induction furnace. Then, these alloys were remelted by Electro-slag remelting (ESR) process and after homogenizing at 1160 °C for 2 h followed by air cooling, were rolled. The effect of Mo on segregation of elements was evaluated with Scanning Electron Microscopy, Linear Analysis, and the mechanical tests. The results showed that the grain boundary segregations of elements in Incoloy 901 superalloy were decreased by increasing of molybdenum content up to 6.7% and the mechanical properties (tensile and hardness properties) were improved. Also, the segregations of elements were increased by increasing the percentage of Mo from 6.7 to 7.5, and the mechanical properties were reduced.

► Grain boundary segregation in superalloys can be decreased by controlling of the chemical composition of alloys.
► One of the most effective element on decreasing of grain boundary segregation is Molybdenum.
► The Mo addition up to 6.7 % have a suitable effect on decreasing of grain boundary segregation of other elements..
► The partitioning coefficients of all elements except Fe and Ni are less than one.