Strengthening Mechanism of Microstructure of Aluminum Bronze Fabricated by Laser Powder Bed Fusion

In this research, the microstructure and tensile properties of Cu–7 mass%Al alloy in the α single-phase region and Cu–10 mass%Al alloy in the (α+γ2) two-phase region on the phase diagram fabricated by laser powder bed fusion (PBF-LB) process and casting were systematically examined, and investigated their microstructure formation mechanism and strengthening mechanism. As a result, in the case of Cu–7 mass%Al alloy, the microfine cellular structures formed by segregation of Al due to the constitutional supercooling by rapid solidification phenomenon in PBF-LB process leaded to high tensile strength and 0.2% proof stress, which were much higher than those of the castings. On the other hand, in the case of Cu–10 mass%Al alloy, the fine β′ martensitic structure with stacking faults formed by rapid solidification phenomena results in lower proof stress and higher tensile strength than the castings. Consequently, it was revealed that the high performance of the Cu–Al alloys is attributed to unique microstructure of the alloys formed by rapid solidification phenomenon in PBF-LB process.