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The aim of this work was to investigate and compare microstructure changes in squeeze cast heat treated Mg–2Y–1Nd–1Zn (WEZ211) and Mg–3Y–2Nd–1Zn–1.5Mn (WEZM3211) alloys. The WEZM3211 alloy was isochronally heat treated in 30 °C/30 min steps from room temperature up to 510 °C, the WEZ211 alloy was first isochronally heat treated in steps of 20 °C/20 min up to 440 °C, quenched and isochronally heat treated again. Phase transformations were investigated by several methods: electrical resistivity was measured after each heating step; transmission electron microscopy was performed in selected states; differential scanning calorimetry was realized in the temperature range 20 – 510 °C. Electrical resistivity curve of the WEZM3211 alloy exhibits a slight decrease around annealing temperature 150 °C and the main drop in the temperature range 240 – 330 °C. This drop can be ascribed mainly to two precipitation processes – formation of thin basal plates of γ´´ phase and subsequently prismatic plates of equilibrium β phase. After annealing at higher temperatures oval particles containing Mn, Y were observed. Electrical resistivity of the WEZ211 alloy shows two decreases connected with formation and development of thin basal plates of γ´phase and ordered γ phase of 14H type.
Keywords: Mg–Y–Nd–Mn–Zn alloys, phase transformations, microstructure, electrical resistivity© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.