Dynamic Precipitation in Mg⁻8.08Gd⁻2.41Sm⁻0.30Zr Alloy during Hot Compression

Dynamic precipitation of Mg⁻8.08Gd⁻2.41Sm⁻0.30Zr (wt %) alloy during hot compression was studied in the present work. The effects of temperature and strain rate on dynamic precipitation, and the effects of dynamic precipitation on dynamic recrystallization (DRX) and microhardness, were systematically analyzed. For this purpose, hot compression tests were conducted at the strain rates of 0.002~1 s^-1 and temperatures of 350~500 °C, with the compaction strain of 70% (ε_max = 0.7). The obtained results revealed that dynamic precipitation occurred during hot compression at 350~400 °C, but did not occur for T ≥ 450 °C. The precipitates were demonstrated to be β-Mg₅Gd with a size of 200~400 nm, and they were distributed in the DRXed region. Dynamic precipitation occurred at strain rates in the 0.002~0.01 s^-1 range, but did not occur when the strain rates were in the 0.1~1 s^-1 range for the hot compression temperature of 350 °C. The relationships between the hot compression temperature (T) and DRXed grain size (lnd), microhardness (H), and DRXed grain size (d^-1/2) of Mg⁻8.08Gd⁻2.41Sm⁻0.30Zr alloy were obtained.