Formation and evolution of the hardening precipitates in a Mg-Y-Nd alloy

The formation and evolution of hardening precipitates in a Mg-Y-Nd (WE43) alloy during artificial ageing at 150 and 210 °C is followed by small angle X-ray scattering (SAXS) measurements, Vickers microhardness tests and transmission electron microscopy (TEM) observations. A quantitative description of the alloy studied during the early and advanced stages of the precipitation sequence is presented. In situ SAXS evolution at 210 °C of the size, volume fraction and number density of the subnanometer and nanometer particles that evolve in the β″ phase was obtained. TEM and microhardness results indicate that the hardening mechanism is based on β″ transformation of pre-precipitates and their growth at 150 °C, while at 210 °C hardening is mainly associated with β″ → β′ transformation.