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 TiB 2 and post-build heat treatment (PHT). The as-printed samples presented a bimodal structure with a refined grain size of ~4.63 μm. The solution-treated sample exhibited a strength-ductility synergy effect, where tensile strength was ~520.3 MPa, elongation was ~9%, which were 133%, 136% of the as-printed sample, respectively. To the best of our knowledge, the 520.3 MPa tensile strength is the highest among all reported LPBFed 2024Al alloy/composites. The high strength is mainly 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 TiB 2 nanoparticles. This manuscript suggests a strategy for developing AMed high-strength aluminum composite via in-situ mixing of nanoparticles and PHT.

Keywords: Laser powder bed fusion, TiB2/Al-Cu-Mg composite, Bimodal structure, Solution treatment, High strength, strengthening mechanisms