Directional migration behavior of alloying element in the rafting process of the single crystal superalloy DD6

Abstract:

This paper investigates the directional migration behavior of the element in the rafting process of the single crystal superalloy DD6 with [001] orientation under 300 MPa at 1000 °C. The microstructure of the single crystal superalloy DD6 is acquired by SEM. The results indicate that the rafting direction of γ′ phase is nearly perpendicular to stress axis. The matrix channel running parallel to the stress axis gets wider, but it will tend to fade away in vertical. Statistical analysis of the alloy components by TEM shows the directional migrations of the elements Al, Re and W in the single crystal superalloy DD6. The element Al spreads to the matrix channel which is parallel to the stress axis, while Re and W diffuse to the matrix channel which is perpendicular to the stress axis.

Key words:Ni-based superalloys; Creep; Directional migration; Diffusion