Characterization of precipitate phases in a Mg–Dy–Gd–Nd alloy

Precipitated phases in a Mg–Dy–Gd–Nd alloy during ageing were studied by using transmission electron microscopy. Observations were performed along some orientations parallel to 〈0 0 0 1〉α and/or 〈1 1 2¯ 0〉α zone axes of the matrix. Results show that the alloy has a rapid ageing response, which can be attributed to the rapid formation of β″ precipitates, occurring in three {1 1 2¯ 0}α planes with DO19 structure; the decreasing of hardness may result from the forming of β1, which forms in three {1 1¯ 0 0}α plates, and the orientation relationship between β1 and the matrix may be described by {1 1¯ 1}β1//{1 1 2¯ 0}α, 〈1 1 0〉β1//〈0 0 0 1〉α; further ageing leads to the formation of β precipitates, which also forms as plates parallel to {1 1¯ 0 0}α, and the orientation relationship between β and the matrix phase is identical to that observed between β1 and matrix phase.