In-situ synchrotron investigation of the phases- and their morphology-development in Mg–Nd–Zn alloys

Abstract

The addition of Zn to the Mg–Nd system improves the yield strength and creep resistance, however its influence on the intermetallic phases in the ternary system is not yet fully understood. Understanding the sequence of phase-formation and phase-evolution during solidification and processing is essential to microstructure design. The solidification was investigated with in-situ synchrotron radiation-diffraction and tomography during cooling from the molten state to 200°C to investigate the phase-formation and transformation characteristics. The solidification starts with α-Mg followed by two distinct intermetallic phases T2 and T3. The results suggest that Zn stabilizes the Mg3Nd phase and accelerates precipitate formation. The dendritic morphology changes during solidification towards coarser shapes, thus impedes feeding and promotes hot tearing.