Fabricated The Magnesium-rare Earth(RE) Alloy By Accumulative Roll-bonding(ARB) Process And Its Properties Of Subsequent Annealing

In this work, an Mg-3Gd(wt. %) was used. The material was subjected to accumulative roll-bonding(ARB) process with different parameters up to 5 cycles to produce fine structured Mg-3Gd alloy sheets. The as-processed material was then annealed at series of temperatures from room temperature to 500 oC. After ARB processing and annealing treatments, the samples were measured by microhardness and tensile test. Optical microscopy and SEM-EBSD were used to characterize the microstructure. The texture was measured by EBSD, and mechanical behaviors were analyzed in detail for the samples processed by second ARB cycle, and annealed under different conditions. The following conclusions can be drawn:① The Mg-3Gd alloy was produced successfully by ARB processing up to 5 cycles with heat-treatment for 8 min at 400 oC before each ARB cycle. Microhardness and strength of the alloy increased significantly after the first cycle and then gradually saturated with further increasing the number of the ARB cycle.② The microhardness of sample produced by first, second and third ARB cycle showed similar tendency, and reached the highest value at 190 oC.③ The sample process by second ARB cycle and annealed at different temperatures showed different mechanical properties. The sample annealed at 190 oC had the highest strength with UTS reaching 321 MPa. The best combination of elongation and strength was obtained after annealing at 290 oC, the yield strength being 211 MPa, about 2.3 times than initial sample, and the elongation was 24.2%, also higher than the initial sample 21.2%. After annealed at 310 oC, the sample had the best excellent elongation, which reaches 36.6%. Yield drop phenomenon appeared after annealing at temperatures from 300 oC to 360 oC.④ After annealing at 290 oC and 300 oC the texture cross the thickness of sample is(0002) plane basal texture with basal pole inclining to rolling direction(RD); The texture through the sample thickness was weakened after annealing at 310 oC and above.⑤ With increasing annealing temperature grain sizes increased. The relationship between the grain size and the yield strength fit the Hall-Petch law. The microstructures after tensile test were different for annealed sample. The 290 oC and 310 oC annealed samples had no obvious deformation twinns, whereas the 360 oC and 340 oC annealed samples showed {10-12}86°<1-210> type tensile twinning.