The microstructural characteristics and decomposition behaviour of rapidly solidified MgNdX (X Al, Si) alloys were investigated by detailed transmission electron microscopy. Rapid solidification of Mg8Nd, Mg8Nd1Al and Mg8Nd1Si produces various types of solidification microstructure depending on the alloy composition, i.e. fine precipitates of Mg3Nd in as-melt-spun Mg8Nd, f.c.c. phase (a = 14.8 Å) at the cell boundaries in as-melt-spun Mg8Nd1Al, and supersaturated α-mg grains with fine particles at the grain boundaries in as-melt-spun Mg8Nd1Si. Annealing of as-rapidly solidified Mg8Nd and Mg8Nd1Si up to 300 °C results in precipitation and coarsening of the Mg3Nd phase. However, no significant change occurs in Mg8Nd1Al on annealing up to 300 °C. On annealing at 400 °C, the pre-existing phase decomposes forming new phases stable at 400 °C, i.e. an f.c.c. phase (a = 5.4 A ̊) in Mg8Nd, an f.c.c. phase a = A ̊, Al2Nd in Mg8Nd1Al, and Mg9Nd in Mg8Nd1Si. The present study shows that of the three alloys investigated, Mg8Nd1Al can have the highest thermal stability owing to the fine, thermally stable Al2Nd particles which appear on annealing at the higher temperature of 400 °C.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering