Precipitation in Mg-Nd-Y-Zr-Ca Alloy during Isothermal Aging: A Comprehensive Atomic-Scaled Study by Means of HAADF-STEM

This paper investigates into the precipitation behavior of Mg-2Nd-1Y-0.1Zr-0.1Ca (wt%) alloy during isothermal aging at 225 degrees C, using atomic-scale HAADF-STEM. The precipitation sequence in Mg-Nd-Y-Zr-Ca is identified as follows: nucleation (LandH) needle-like precipitates composed of (M), (T), and (C) structures as repetitive units(1)equilibrium . From an engineering point of view, the atomic-size precipitates that distribute uniformly have a significant strengthening effect. In addition, the present study discusses three findings concerning the novel structures observed in the alloy: two types of interaction between needle-like precipitates are observed; the previously reported structure is doubted according to the analysis of the defects characterized from calcium is observed to be enriched in 1 precipitates and along grain boundaries.