In the context of global carbon neutrality, the application of lightweight magnesium alloys is becoming increasingly attractive. In this study, selective laser melting(SLM) was employed to achieve nearly full dense an...In the context of global carbon neutrality, the application of lightweight magnesium alloys is becoming increasingly attractive. In this study, selective laser melting(SLM) was employed to achieve nearly full dense and crack-free AZ91D components with fine equiaxed grain structure. The formation mechanism of typical pore defects(gas pore, lack-of-fusion pore and keyhole pore) and melting modes(keyhole mode and conduction mode) were systematically studied by varying the laser power and scanning speed. The morphology and volume fraction of the pores under different processing conditions were characterized. A criterion based on the depth-to-width ratio of the melt pool was established to identify different melting modes. The strength and ductility(tensile strength up to 340 MPa and uniform elongation of 8.9%)of the as deposited AZ91D are far superior to those of the casting components and are comparable to those of its wrought counterparts.The superior balance of strength and ductility of SLMed AZ91D, as well as the negligible anisotropic properties are mainly ascribed to the extremely fine equiaxed grain structure(with average grain size of ~1.2 μm), as well as the discontinuous distribution of β-Al_(12)Mg_(17) phases. It thus provides an alternative way to fabricate high-strength magnesium alloys with complex geometry.展开更多
基金the financial support from the National Natural Science Foundation of China [51805415,51922048]China Postdoctoral Science Foundation [2019M663682]+2 种基金China Postdoctoral Science Foundation [Grant number 2019M663682]Young Elite Scientists Sponsorship Program by CAST [Grant number 2021QNRC001]the fund of State Key Laboratory of Long-life High Temperature Materials (DECSKL202104)。
文摘In the context of global carbon neutrality, the application of lightweight magnesium alloys is becoming increasingly attractive. In this study, selective laser melting(SLM) was employed to achieve nearly full dense and crack-free AZ91D components with fine equiaxed grain structure. The formation mechanism of typical pore defects(gas pore, lack-of-fusion pore and keyhole pore) and melting modes(keyhole mode and conduction mode) were systematically studied by varying the laser power and scanning speed. The morphology and volume fraction of the pores under different processing conditions were characterized. A criterion based on the depth-to-width ratio of the melt pool was established to identify different melting modes. The strength and ductility(tensile strength up to 340 MPa and uniform elongation of 8.9%)of the as deposited AZ91D are far superior to those of the casting components and are comparable to those of its wrought counterparts.The superior balance of strength and ductility of SLMed AZ91D, as well as the negligible anisotropic properties are mainly ascribed to the extremely fine equiaxed grain structure(with average grain size of ~1.2 μm), as well as the discontinuous distribution of β-Al_(12)Mg_(17) phases. It thus provides an alternative way to fabricate high-strength magnesium alloys with complex geometry.
