Increasing the ductility of an Al-Cu-TiB2 composite by additive manufacturing

To overcome the strength-ductility trade-off, Al2618 alloy that is reinforced with in-situ TiB2 particles is processed by additive manufacturing (AM), specifically laser powder bed fusion (LPBF), with the assistance of 0.1%Sc. While a ductility of 7% is maintained, the yield strength (YS) and ultimate tensile strength (UTS) are increased by 88% and 59% to 370 MPa and 450 MPa, respectively. The improvement is achieved through an enhanced grain refinement of the aluminum matrix and the uniform dispersion of the TiB2 reinforcing particles. The laser beam modifies the reinforcing particles and promotes the nucleation of aluminum grains in the melt pool under a high cooling rate that restricts the growth of the aluminum grains. Meanwhile, the comparable sizes of the matrix grains and the reinforcing particles block the motion of dislocations effectively, strengthening the AM products.