Superior strength-ductility synergy in additively manufactured beryllium-aluminum alloy via dual-phase coordinated deformation

Abstract

Beryllium-aluminum (Be-Al) alloys possess low density and high specific stiffness, promising for aerospace applications, yet limited by low strength and poor ductility. This study introduces a novel Be-Al alloy, fabricated via laser-directed energy deposition with Mg and Si additions, exhibiting superior strength and ductility. The resultant dual-phase (Be and Al) microstructure benefits from Mg/Si addition, rapid solidification, and intrinsic heat treatment during additive manufacturing. These factors strengthen the Al phase and mitigate deformation mismatch between phases. Consequently, compared to cast counterparts, this alloy achieves a ∼120% increase in strength and a ∼200% improvement in ductility. GRAPHICAL ABSTRACTSix microstructure maps, two fracture mechanism micrographs, and two mechanical property graphs comparing AM Be-Al and Be-Al-Mg-Si alloys.The figure shows a schematic layout with microstructure maps on the left, fracture mechanism micrographs in the center, and mechanical property graphs on the right for additively manufactured beryllium aluminium and beryllium aluminium magnesium silicon alloys. The upper left group, labeled Microstructure in AM Be-Al alloy, contains several orientation and phase maps with elongated grains, a legend that distinguishes face centered cubic aluminium and hexagonal close packed beryllium, and a grain boundary key that separates low angle and high angle boundaries. The lower left group, labeled Microstructure in AM Be-Al-Mg-Si alloy, shows similar elongated features with additional clusters and three elemental maps marked Al, Si, and Mg, each covering the same rectangular field. The central column, labeled Fracture mechanism, presents two grayscale fracture surface micrographs. The upper one, titled AM Be-Al, shows a flat region transitioning into a textured region with elongated striations, and an arrow with text indicating fracture direction and plastic deformation marks. The lower micrograph, titled AM Be-Al-Mg-Si, shows a comparable arrangement, with an arrow and text again marking the fracture direction and plastic deformation zone. The right column, labeled Mechanical property, contains two graphs. The top graph plots engineering stress in megapascals on the vertical axis against engineering strain in percent on the horizontal axis, from 0 to about 12 percent. It contains 2 curves, one for Be-Al and one for Be-Al-Mg-Si, with an arrow labeled Increasing 100 percent pointing from the lower Be-Al curve to the higher Be-Al-Mg-Si curve. The bottom graph plots ultimate tensile strength in megapascals versus elongation in percent, comparing data groups for Cast, Powder Metallurgy, AM Be-Al, and AM Be-Al-Mg-Si, with separate symbol clusters and an arrow pointing from the Cast region toward AM Be-Al-Mg-Si. All data are approximate. Impact statement Additively manufactured Be-Al-Mg-Si alloy achieves ∼120% higher strength than cast counterparts while retaining high ductility, owing to Al-phase strengthening and exceptionally coordinated deformation between Be and Al phases.