Stabilizing post-yielding behavior of a stretching dominated lattice structure through microstructural optimization

TL;DR

This study explores how microstructural modifications in Ti-14 Mo alloy lattice structures influence their post-yielding stability, aiming to enhance energy absorption through tailored microstructures.

Contribution

It demonstrates that microstructural optimization can improve the plastic buckling resistance of lattice structures, advancing defect-tolerant additive manufacturing materials.

Findings

Microstructural changes affect mechanical response and stability.

Heat treatments lead to different microstructures with distinct properties.

Optimized microstructures improve energy absorption and stability.

Abstract

We investigate the effect of the microstructure on the mechanical response of lattice structures made of a defect tolerant Ti-14 Mo binary alloy fabricated by Electron Powder Bed Fusion. Some of the lattice structures were subjected to different heat treatments to compare different microstructures: a two-phase $\alpha$+$\beta$ microstructure inherited from the fabrication (as-built), a full $\beta$-metastable microstructure, and a $\beta$-metastable microstructure strengthened via nanoprecipitation of the $\omega$iso phase. We demonstrate that the macroscopic mechanical behavior of one of the most popular stretching-dominated lattice structure, namely the octet-truss, can be tailored through microstructural optimization by increasing the tolerance to plastic buckling of the constitutive struts. Defect-tolerant materials pave the way towards lattice structures fabricated by additive manufacturing with optimized energy absorption performances.