Hierarchical microstructures, not grain refinement alone, push aluminum to 728 MPa or 30.4% elongation
Asked:
“Find the processing parameters, alloying elements, and microstructural features of aluminum alloys that improve strain to failure and tensile strength.”
Eight experimental studies of optimized aluminum alloys, spanning additive manufacturing, friction-stir and severe deformation, and advanced casting. Reported ultimate tensile strength runs 254–728 MPa (mean 454.5 MPa) and tensile elongation 5.1–30.4% (mean 18.1%). Arrows trace the four studies with a directly comparable baseline.
Additive manufacturingFriction-stir / severe deformationCastingBaseline → optimized (where reported)
Mechanism map: processing → alloying → microstructure → result
Findings
Design rules
Combine mechanisms: solid solution or clustering, dense nanoscale precipitates (η′, Al3(Sc,Zr), Al3Ti/Al2Cu) and grain-boundary or particle pinning stack strength without exhausting ductility from one source.
Keep a soft reservoir: heterogeneous or bimodal grain populations — and even deliberately retained coarse Al — sustain strain hardening and back stress, delaying necking.
Suppress crack starters: heal porosity and cracks (FSP), reduce segregation, avoid brittle continuous boundary films, and keep interfaces strong; ductility gains track defect cleanliness as much as grain size.
Use processing as the lever: rapid solidification with scan rotation, short solution + peak aging, cryogenic severe deformation, and ultrasound + squeeze casting each build the hierarchy that lifts both metrics together.
The eight optimized conditions
Strategy
Alloy and role of additions
UTS, MPa
Elong., %
Comparator
Source
Synthesis of 8 experimental studies (one optimized condition each) on strength–ductility improvement in aluminum alloys; UTS in MPa and tensile elongation / strain to failure as reported by each paper, on differing alloy systems and specimen geometries, so values are not directly rank-equivalent. Baseline arrows shown only where the paper gave a comparable baseline; the CAEB aging schedule was not recovered. Full processing recipes shortened for space; complete parameters in the sources.