Towards Co-Based Superalloys: A Combinatorial Approach to Assess the Effect of Ta and W On Co-Al-X (X=Ta, W) System

The interest in a new class of Co-based superalloys with high temperature properties comparable to that of Ni-based alloys has prompted a systematic investigation of the influence of different alloying elements on the microstructural evolution and mechanical properties of these superalloys. Laser Engineered Net Shaping (LENS™) may be exploited as a combinatorial technique to conduct systematic studies of compositionally graded materials in order to understand the role of various elements on the microstructure. This technique has been applied to Co-based superalloys to accelerate the understanding of composition-structure-property relationships in these emerging materials. A compositionally graded quaternary alloy, Co-Al-xW-yTa, was produced using the LENS™ with a linear increase in Ta marked by an equal reduction in the W content. The alloy was heat treated and characterized using several characterization techniques including SEM, TEM and 3D atom probe tomography in order to assess the role of composition variation on the microstructural evolution and phase stability of these alloys.