Si-Assisted Solidification Path and Microstructure Control of 7075 Aluminum Alloy with Improved Mechanical Properties by Selective Laser Melting

The construction and application of traditional high-strength 7075 aluminum alloy (Al7075) through selective laser melting (SLM) are currently restricted by the serious hot cracking phenomenon. To address this critical issue, in study, Si is employed to assist SLM printing Al7075. energy density during optimized, effects element on solidification path, relative density, microstructure mechanical properties Al7075 studied systematically. With modified dense with refined grain size semi-continuous precipitates network at boundaries, which consists fine Si, β-Mg2Si, Q-phase θ-Al2Cu, phenomenon effectively improved. As a result, tensile strength SLM-processed Si-modified can reach 486 ± 3 MPa, high ~ 99.4%, yield 291 8 fracture elongation (6.4 0.4)% hardness 162 2 (HV0.2) 112.5 J/mm3. main strengthening mechanism modification demonstrated be synergetic enhancement refinement, solution strengthening, load transfer, dislocation strengthening. This work will inspire more new design alloys SLM.