Achieving excellent strength of the LPBF additively manufactured Al–Cu–Mg composite via in-situ mixing TiB2 and solution treatment

Abstract

Additively manufactured (AMed) structure with superior strength is urgently required in Al alloy engineered products. Here, we reported a laser powder bed fusion (LPBF) AMed Al–Cu–Mg composite with excellent strength obtained by in-situ mixing TiB2 and post-build heat treatment (PHT). The as-printed samples presented the bimodal structure with a refined grain size of ∼4.63 μm. The solution-treated sample exhibited an excellent combination of strength and ductility (tensile strength ∼520.3 MPa, uniform elongation ∼9%), which were 133%, 136% of the as-printed sample, respectively. Such tensile strength was the highest among all reported LPBFed 2024Al alloy/composites. In detail, the high strength can be attributed to grain boundary strengthening caused by the refined equiaxed-columnar bimodal structure, solution strengthening caused by the dissolved elements, load-bearing strengthening and Orowan-strengthening caused by TiB2 particles. Therefore, this manuscript should suggest a strategy for developing AMed high-strength aluminum composite via in-situ mixing of particles and PHT.