The invention discloses a method for improving the medium-temperature strength of an additive manufacturing Al-Si
alloy, and belongs to the field of
metal materials. According to the method, the Al-Si
alloy serves as a base body, micron-sized AlB2 and Ti
powder are added,
laser irradiation energy in the additive manufacturing process is used for enabling the micron-sized AlB2 and Ti
powder to react, and nanoscale TiB2 and D022-Al3Ti strengthening phases are synthesized in situ so that the medium-temperature strength of the material can be improved. By optimizing the content of the components, the adding proportion of the AlB2
powder and the adding proportion of the Ti powder are controlled to be 1.20-1.60 wt.% and 1.80-2.40 wt.% respectively, and the
mass ratio of the AlB2 powder to the Ti powder is 2: 3. Through the synergistic effect of the two nanoscale second phases, the
alloy can have high strength in a medium-temperature environment without post-heat treatment, and meanwhile, the high percentage elongation after fracture is kept. The yield strength of the alloy in the environment of 300 DEG C reaches 190 MPa, the tensile strength reaches 200 MPa, the
ductility reaches 10%, and the strength upper limit of the
selective laser melting near-eutectic Al-Si alloy in the
working environment of 300 DEG C is broken through. The
mechanical property of the aluminum alloy is comparable with that of Al-Ni, Al-Ce and other heat-resistant aluminum alloys prepared through
selective laser melting, and the aluminum alloy is lower in cost and lighter in density.