Abstract:In this study, additive friction stir deposition (AFSD) experiments of Mg-Gd-Y-Zr (GW83K) rare earth magnesium alloy were carried out using a pressure-controlled solid-phase friction extrusion additive manufacturing equipment. The effects of aging treatment on the microstructure and mechanical properties of the deposited layer were systematically investigated. The results indicate that fully dense GW83K rare earth magnesium alloy deposited specimens without macroscopic defects are obtained under the process parameters of a spindle speed of 250 rpm and a traverse speed of 100 mm/min. Compared with the original bar stock, the deposited zone presents an obvious mixed grain structure. The average grain size of the local coarse-grained region on the advancing side of the deposited layer is 17.37±7.29 μm, whereas the average grain size in most regions of the middle part and the retreating side is significantly refined to 5.66±2.58 μm and 4.36±2.32 ?m. After aging treatment at 215 ℃ for 30 h, the as-deposited specimens possess a uniform and fine grain structure. The hardness increases from 85.8 HV to 109.5 HV; the yield strength (YS) and ultimate tensile strength (UTS) reach up to 329.5±11.7 MPa and 384.25±7.5 MPa, respectively, with an elongation of 8.125±0.25%. The tensile fracture surfaces of the specimens exhibit a ductile-brittle mixed fracture characteristic. This study verifies that aging treatment precipitates fine β" strengthening phases on the basis of retaining the fine grains of the deposited layer, which significantly improves the strength-ductility synergy of the GW83K rare earth magnesium alloy fabricated by AFSD.