Influence of temperature of ECAP processing on the microstructure and microhardness of as-cast AX41 alloy
Abstract
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 degrees C and 250 degrees C up to N = 8 passes via route Bc.
The original grain size of 200 mu m was found to decrease with increasing number of passes at both temperatures. After 8 passes, the grain size of 1.4 mu m and 2.6 mu m was obtained at 220 degrees C and 250 degrees C, respectively.
This difference was attributed to the suppressed dynamic recrystallization for N > 2 caused by substantial decrease in dislocation density of 101 over bar 0112 over bar 0 pyramidal -type edge dislocations and more pronounced high-temperature grain growth at 250 degrees 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.