Effect of Solution Treatment Time on Microstructure Evolution and Properties of Mg-3Y-4Nd-2Al Alloy.

In order to explore the microstructure evolution of an Mg-RE alloy refined by Al during solution treatment, an Mg-3Y-4Nd-2Al alloy was treated at 545 °C for different time periods. Phase evolution of the alloy was investigated. After solution treatment, the Mg-RE eutectic phase in the Mg-3Y-4Nd-2Al alloy dissolves, the granular Al 2 RE phase does not change, the acicular Al 11 RE 3 phase breaks into the short rod-like Al 2 RE phase, and the lamellar Al 2 RE phase precipitates in the grains. With the extension of solution time, the precipitated phase of the lamellar Al 2 RE increased at first and then decreased, and its orientation relationship with the matrix is <112>Al2RE//<21¯1¯0>Mg and {111}Al2RE//{0002}Mg. The undissolved granular Al 2 RE phase can improve the thermal stability of the alloy grain by pinning the grain boundary, and the grain size did not change after solution treatment. Solution treatment significantly improved the plasticity of the alloy. After 48 h of solution treatment, the elongation increased to 17.5% from 8.5% in the as-cast state.