Caroline Antion, Patricia Donnadieu, Jean-Jacques Blandin, Françoise Bley, Alexis Deschamps, Catherine Tassin, Alexander Pisch
March 1, 2013
Precipitation microstructures and mechanical properties of two new Mg–Mn–Y–Gd alloys have been studied. Small Angle X-ray Scattering and Transmission Electron Microscopy carried out on homogeneous and aged states (200°C and 250°C) have revealed Guinier–Preston zones formed from the homogeneous state at ambient temperature and first stages of precipitation consisting in DO 19 type monolayer precipitates. These ultrafine precipitates show further organisation leading to the orthorhombic β′ phase. Peak-hardness microstructure is characterised by a high density of connected β′ precipitates. Overaged samples show a high level of mechanical strength and creep resistance. The related microstructure consists of stable β′ phase precipitates forming connected strings giving rise to a local strain within the matrix. Comparison with previous studies confirms the strong relationship between rare earth elements choice, precipitation microstructure and mechanical resistance.