Laser powder bed fusion of a novel high strength quasicrystalline Al–Fe–Cr reinforced Al matrix composite

Quasicrystal (QC)-reinforced metal matrix composites fabricated by rapid solidification present promising new opportunities to develop high-strength alloys with multiple functions. In this research, specially designed Al–Fe–Cr samples possessing an Al–Fe–Cr quasicrystal-reinforced Al matrix structure were manufactured using a laser powder bed fusion (LPBF) process. Based on the optimized process parameters of laser scanning speed and hatch distance, an almost dense (99.8%) free-crack sample was obtained with the multiscaled heterogenous structure induced by the nonuniform rapid solidification in a single molten pool. The results show that nanosized Al–Fe–Cr quasicrystalline particles of different sizes are heterogeneously distributed in the α-Al columnar grain structure. In detail, the coarse flower-like and spherical QC particles can be observed at the molten pool boundary, and the fine spherical Al–Fe–Cr QC is located inside the laser fusion zone. The orientation relationship between the Al matrix and the icosahedral Al–Fe–Cr QC is as follows: Al [ ​− ​112 ] ∥ i5 with a semicoherency feature. The novel designed LPBF-processed Al–Fe–Cr alloy exhibits high mechanical strength due to the ultrafine multireinforced microstructure-induced Orowan strengthening effect. For instance, the ultimate tensile strength, yield strength and elongation of the sample processed with LPBF are 530.80 ​± ​3.19 ​MPa, 395.06 ​± ​6.44 ​MPa, and 4.16% ​± ​0.38%, respectively. The fractographic analysis shows that the fracture mechanism presents a combination of ductile‒brittle fracture.