Wire-based friction stir additive manufacturing towards isotropic high-strength-ductility Al-Mg alloys

Abstract

The formation of eutectic Al-Mg2Al3 phases along the grain boundaries makes it difficult to improve the mechanical properties of high-magnesium-content aluminum alloys. Here, wire-based friction stir additive manufacturing(W-FSAM) was proposed as a novel solid-state additive manufacturing technology. The shearing, transport, and thermo-plasticisation processes of the deposited materials were achieved by a rotational tool and a stationary barrel. The original Mg2Al3 phases were refined and dissolved into the matrix and formed supersaturated solid solution structures. The refined grains with a diameter of 1.27 ± 0.64 μm were achieved through the dynamic recrystallization process. The components achieved isotropic mechanical properties due to the homogeneous equiaxed fine-grain structure. The ultimate tensile strength reached 415 ± 11 MPa with an elongation of 31.0 ± 2.0%, superior to the commercial 5xxx products. The enhanced strain hardening capacity was achieved by the suppressed emission of dislocations from grain boundaries and the interaction between the supersaturated solid solute atoms and mobile dislocation.

Keywords

• Friction stir additive manufacturing
• Al-Mg alloys
• high magnesium contents
• mechanical properties
• strain hardening capacity