Microstructure and mechanical properties of Ti modified 7075 aluminum alloy fabricated by selective laser melting

Abstract

In this study, Ti/7075 aluminum alloy samples were successfully prepared by selective laser melting (SLM). The effects of process parameters and solution treatment on the microstructure and mechanical properties were studied. Research shows that when the laser power is 270W, the scanning speed is 600mm/s, and the laser energy density is 166.67J/mm3, the density of the Ti-added composite powder sample increases from 96.63% to 97.30% compared to the 7075 sample. Ti reacts in situ to generate the Al3Ti phase during the SLM process. Al3Ti has a heterogeneous nucleation effect, which can promote the transformation of columnar crystals into equiaxed crystals and inhibit the occurrence of anisotropy and hot cracks to a certain extent. The average grain size of the sample was refined from 18.71 μm to 2.24μm. Under the optimal process parameters, the room temperature tensile strength of the as-deposited Ti/7075 aluminum alloy is 358MPa, and the elongation is 15.5%. After solution treatment, the performance is further improved, the tensile strength is increased to 442MPa, and the elongation is increased to 20.1%.