Excellent strength–ductility balance of Sc-Zr-modified Al–Mg alloy by tuning bimodal microstructure via hatch spacing in laser powder bed fusion

The bimodal microstructure, which comprises ultrafine grains (UFGs) forming along the melt pool boundary and relatively coarse inside pool, is a characteristic of Sc-Zr-modified Al–Mg-based alloy (Scalmalloy) microstructure manufactured using laser powder bed fusion (LPBF). Focusing on this microstructural feature, we investigated improvement in mechanical properties LPBF-fabricated Scalmalloy by tailoring volume fraction UFGs. Our approach was to decrease hatch spacing (d) from 0.1 0.04 mm, while UFGs increased 34.6 ± 0.6 % (d = mm) 59.5 0.5 0.06 mm). tensile yield stress 296 9 380 6 MPa mm), maintaining large elongation (14.8 1.2 %). were superior those cast counterparts 2.9 4.0 times, respectively. In sample with d pores formed owing excessive thermal energy input. Additionally, multiple strengthening mechanisms as-fabricated alloy. This first study improve optimizing track-to-track interval tuning UFG fraction.