The Effect of Heat Treatment on Local Mechanical Properties of Laser Powder Bed Fused and Hot Isostatically Pressed Al-Cu-Mg-Ag-TiB2 (A20X) Aluminum Alloy

A20X is a high-strength aluminum alloy where TiB2 particles reinforce an Al-Cu-Mg-Ag matrix. In this study, a recently developed composition of Al-Cu-Mg-Ag-TiB2 (A20X) alloy, fabricated by laser powder bed fusion (L-PBF), is investigated under hot isostatically pressed (HIPed) condition. To minimize the L-PBF induced defects (e.g., porosity, lack of fusions), the HIP cycle [ramp at 5/10°C, dwell for 2 h at 103 MPa and uniform rapid cooling (URC®) applied to room temperature] is carried out at 510°C. The stability of the microstructure in crack-free conditions is significantly aided by the HIP cycle. However, as the studied alloy is responsive to precipitation hardening, the HIPed material still needs optimization of its microstructure through carefully designed heat treatments. Micromechanical properties of the materials in all conditions (as-HIPed and two heat treatments) are studied employing depth-sensing nanoindentation testing to assess the variation of location-dependent local mechanical properties of the materials. Microstructural characterization through optical and scanning electron microscopy (SEM) is carried out. The significance of post-processing procedures (such as heat treatments and HIP) and the relationship among processing, post-processing, microstructure and mechanical properties are clarified by this work.