Laser powder bed fusion of a Co–Al–W-based composite: Effects of Y2O3 nanoparticles on crack elimination, microstructure and mechanical properties

Abstract

In order to meet the aerospace industry's growing demand for higher-temperature and more-efficient materials, Co–Al–W-based superalloy was invented in 2006 and is expected to become the next generation of potential superalloys for aero engines. Laser powder bed fusion, as a type of additive manufacturing technology, is considered to be an advanced method for manufacturing aerospace components. However, for Co–Al–W-based superalloy, cracking commonly occurs during this process. To solve the cracking in the non-weldable Co–Al–W-based superalloy during laser powder bed fusion, 0.5 wt% Y2O3 nanoparticles were added to this alloy, forming a Co–Al–W-based composite. The results show that the cracks that formed in the Co–Al–W-based superalloy were attributed to the solidification cracking owing to the formation of the Laves phase in the inter-dendritic region. The added Y2O3 nanoparticles presented a stable chemical state without extra reactions with other elements during the laser powder bed fusion process. They played a heterogeneous nucleation role to induce columnar to equiaxed transition, where the microstructure was refined, and the cracks were eliminated. As a result, the tensile performance was dramatically improved.