Influence of Sr Modifier in Microstructure and Tensile Properties of AlSi10Mg Alloy Fabricated by Laser Powder Bed Fusion Process

초록

AlSi10Mg containing 150 ppm Sr was fabricated via the laser powder bed fusion (LPBF) process. The effect of Sr element addition on the microstructure and tensile mechanical properties of an LPBF-built AlSi10MgSr alloy was investigated. Stress-relieving (SR) heat treatment was carried out on the fabricated alloy at 225 °C for one hour, followed by air cooling. Thermal analysis showed that adding Sr decreased the eutectic onset temperature of the conventional AlSi10Mg alloy. Initial microstructure analysis revealed a fine equiaxed cellular structure in the as-built specimen composed of new spherical Si particles (~ 0.12 μm). The stress-relieved heat-treated (HT) specimen also exhibited a large number of nanosized Si precipitates (~ 39 nm), along with newly formed spherical Si particles (~ 0.09 μm), which were uniformly distributed within the α–Al grains.The modified AlSi10MgSr alloy of the as-built and HT samples exhibited the high ultimate tensile strengths of 456.3 ± 11.3 MPa and 465.3 ± 4.7 MPa, respectively. The enhanced mechanical properties were attributed mainly to the significant grain refinement of α–Al grains and Al–Si eutectic cells because of the addition of Sr and the Orowan strengthening effect by nano-sized Si precipitates. The hardening mechanism was explained in terms of the precipitation hardening of second-phase particles and the heterogeneous nucleation of particles during the LPBF solidification process. © The Author(s) under exclusive licence to The Korean Institute of Metals and Materials 2025.

키워드