Microstructural development of Powder Metallurgy Cobalt-based superalloys processed by Field Assisted Sintering Techniques (FAST)

Abstract

This study reports the microstructural evolution, physical and mechanical properties of cobalt-based superalloys processed from mechanical alloyed powders and consolidated by field-assisted sintering techniques (FAST). After an initial thermodynamic simulation of the ternary diagram by Thermocalc (R) to determine the composition, a sequential milling process was carried out at room temperature up to 40 h milling of two different alloying systems: CO-12Al-10W (at%) and Co-12Al-10W-2Ti-2Ta (at%). Characterization of the powders was performed by using X-Ray diffraction, scanning electron microscope with energy-dispersive X-ray spectroscopy (EDS) and particle-size analyzer. Consolidated samples were also characterized in terms of density, microhardness and hardness. In order to promote the dual gamma/gamma microstructure, both alloys were aged after solution annealing heat treatment, improving a new route of consolidation with a new level of performance.