Influence of temperature of ECAP processing on the microstructure and microhardness of as-cast AX41 alloy

The influence of the temperature of ECAP processing on the microstructure and mechanical properties of commercial as-cast AX41 magnesium was investigated. ECAP processing was conducted at temperatures of 220 °C and 250 °C up to N = 8 passes via route Bc. The original grain size of 200 μm was found to decrease with increasing number of passes at both temperatures. After 8 passes, the grain size of 1.4 μm and 2.6 μm was obtained at 220 °C and 250 °C, respectively. This difference was attributed to the suppressed dynamic recrystallization for N > 2 caused by substantial decrease in dislocation density of \( \left\{ {10\bar{1}0} \right\}11\bar{2}0 \) prismatic and \( \left\{ {10\bar{1}1} \right\}11\bar{2}3 \) pyramidal <a>-type edge dislocations and more pronounced high-temperature grain growth at 250 °C. Despite the different grain sizes, similar crystallographic textures and dislocation densities were observed at both temperatures after 8 passes. The microhardness values increased up to 4 passes at both temperatures in accordance with the variation of the grain size, indicating the dominance of Hall–Petch strengthening.