A high strength AlSi10Mg alloy fabricated by laser powder bed fusion with addition of Al[sbnd]Ti[sbnd]C[sbnd]B master alloy powders

Abstract

In this work, a feasible method to improve the mechanical performance of laser powder bed fusion (L–PBF) fabricated AlSi10Mg alloy has been developed by the addition of AlTiCB master alloy powders into AlSi10Mg alloy powders. During L–PBF process, the AlTiCB alloy powders could release numerous sub–micron and nanosized B atoms doped TiC (TiCB) particles, which will act as the in–situ nucleation sites for α–Al grains. A textureless microstructure consisting of equiaxed α–Al grains with average size of 3 μm was obtained in the L–PBF fabricated AlSi10Mg alloy decorated with 10 wt.% of AlTiCB alloy powders (AlSi10MgTiCB). Fine AlSi cellular structure composed of small eutectic Si particles (~30 nm) was also detected. Besides, the nano–sized Si precipitates (~10 nm) distributed uniformly inside the α–Al grains were also observed. The L–PBF fabricated AlSi10MgTiCB alloy exhibits high ultimate tensile strength of 488 ± 6 MPa and total elongation of 10.1 ± 2.2%. The enhanced mechanical properties are supposed mainly attributing to the significant refinement of α–Al grains and AlSi eutectic cells due to the addition of TiCB inoculants, as well as the particles reinforcement effect by TiCB and Si precipitates. The method proposed in this work is promising, since it is easy to operate, which requires only mechanically mixing two Al–based powders. This work may also provide new insights for designing Al alloy powders suitable for L–PBF process, using particle–contained Al–based master alloys to decorate other commercial powders, such as 2 × × × and 7 × × × series alloys.