Precipitation in lean Mg–Zn–Ca alloys
نویسندگان
چکیده
While lean Mg–Zn–Ca alloys are promising materials for temporary implants, questions remain on the impact of Zn and Ca microstructure. In this context, precipitation in Mg-1.5Zn-0.25Ca (in wt.%), initially extruded at 330°C, towards Mg–Ca binary precipitates or Ca–Mg–Zn ternary was probed a multiscale correlative approach using atom probe tomography (APT) analytical transmission electron microscopy (TEM). Particular focus set precipitate phase whose structure is debated. as-extruded material, made hexagonal C14 Mg2Ca containing up to about 3 at.% Zn. The ones based Ca2Mg5Zn5 prototype with composition close Ca3Mg11Zn4, as deduced from atomically resolved EDS mapping scanning TEM imaging, supported by simulations. sequence scrutinized upon linear heating room temperature 375°C, starting solutionized material. Three exothermic differential calorimetry (DSC) peaks were observed, respectively 125, 250 320°C. Samples taken after peak decays, 205, 260 375°C structural analysis. At 205°C, APT analysis revealed Ca-rich, Zn-rich Zn?Ca-rich clusters nm size number density 5.7 × 1023 m?3. 260°C, showed mono-layered Guinier?Preston (GP) zones 8 1.3 larger highly coherent elongated found, 50 nm. They occur Ca2Mg6Zn3 precipitates, TEM-based energy dispersive X-ray spectroscopy (EDS) nanodiffraction TEM. Here, outnumber ones, while material which corresponds well calculated diagram. We correlated microstructure hardness Vickers testing. largest hardening relates end 125°C DSC thus GP zones, outperform induced nanometer-sized intermetallic particles. complexity discussed.
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ژورنال
عنوان ژورنال: Acta Materialia
سال: 2022
ISSN: ['1873-2453', '1359-6454']
DOI: https://doi.org/10.1016/j.actamat.2022.118223