The evolution and characterizations of Al3(ScxZr1-x) phase in Al–Mg-based alloys proceeded by SLM

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 824; p. 141863
• Main Authors: Zhao, Junhao, Luo, Liangshun, Xue, Xiang, Liu, Tong, Luo, Lei, Wang, Binbin, Wang, Yanan, Wang, Liang, Su, Yanqing, Guo, Jingjie, Fu, Hengzhi
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 08.09.2021; Elsevier BV
• Subjects: Aluminium; Aluminum; Al–Mg–Mn-Sc-Zr alloy; Chemical precipitation; Crystallography; Dispersions; Enthalpy; First principles; Grain boundaries; Grain growth; Grain refinement; Laser beam melting; Magnesium base alloys; Mathematical analysis; Nucleation; Precipitates; Scandium; Selective laser melting; TEM; Ultimate tensile strength; Zirconium; Aluminium; Al–Mg–Mn-Sc-Zr alloy; Selective laser melting; Precipitates; TEM
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2021.141863

The addition of Sc and Zr endows selective laser melted Al–Mg-based alloys with exceptional properties, which are predominately related to the Al3(ScxZr1-x) precipitates. The Al3(ScxZr1-x) precipitates formed in different stage of processing are identified as primary- Al3(ScxZr1-x) and aged- Al3(ScxZr1-x) according to different crystallographic characteristics. The experimental results show most of primary Al3(ScxZr1-x) particles located in the grain boundaries with incoherent interface and irregular shape, which is seldom reported in conventional casting. In contrast, the subsequent aging brings out more spherical Al3(ScxZr1-x) with coherent interface emerged in the grains. Combined the first-principle calculations with pseudo binary-diagram, we search the possible structures of Al3(ScxZr1-x) based on their formation enthalpy and binding energy, whose space group should be altered as Sc enters the Al3Zr (DO23) dispersoids. The most possible structure of primary Al3(ScxZr1-x) phase is evaluated as Al12Sc3Zr, and the calculated crystallo-graphic parameters are consistent with the experimental results. As the primary Al3(ScxZr1-x) is hard to act as nucleation particle, it can be inferred that the grain refinement resulting from the modification and hindrance of these particles during grain growth. A corresponding ultimate tensile strength and ductility is separately about 521.26 ± 12.30 MPa and 15.83 ± 0.94% after aging at 325 °C for 4 h. The results demonstrate the difference between the primary Al3(ScxZr1-x) and the aged Al3(ScxZr1-x) as well as the formation of primary Al3(ScxZr1-x), which offer a new idea to design new alloy for additive manufacturing. •The primary Al3(ScxZr1-x) is observed in SLM proceeded Al–Mg-based alloy.•The primary Al3(ScxZr1-x) has semi-coherent interface with α-Al.•The space group of primary Al3(ScxZr1-x) is altered as Sc enters Al3Zr dispersoids.•The grain refinement resulting from the modification and hindrance of primary Al3(ScxZr1-x).