Effect of microstructure on the effectiveness of hybridization on additively manufactured Inconel718 lattices

Abstract

This work aims to investigate the effect of the material microstructure on the effectiveness of hybridization in additively manufactured Inconel718 strut-based lattices. Two microstructures, namely the as-built solid solution and a peak aged condition, are coupled with three hybrid architectures formed by alternating face centred cubic (matrix) and octet-truss (reinforcement) domains containing 1, 8, and 64 unit cells. Digital image correlation is utilized to map the local strain distribution during compression, and finite element analysis is utilized to map stress localization. It is shown that in the as-built condition the mechanical behavior of all the hybrid lattices was very similar to that of the single-oriented components, irrespective of the reinforcement size. In the peak-aged lattices, on the contrary, including octet-truss reinforcements of sufficiently small size resulted in an increase in mechanical stability, damage tolerance, and absorbed energy, as interphase boundaries act as obstacles to shear band propagation. It is also shown that effect of hybridization is a function of the size of the reinforcements. In particular, below a critical size, the lattice behaves as a reinforced “single-phase” structure, rather than a two-phase architecture. This work defines guidelines for the design of robust lattices manufactured by laser powder bed fusion.

Keywords

• Microstructure
• Mechanical behavior
• Additive manufacturing
• Two phase lattice
• Inconel718