Hardening precipitation in a Mg–4Y–3RE alloy

• Published in: Acta materialia Vol. 51; no. 18; pp. 5335 - 5348
• Main Authors: Antion, C., Donnadieu, P., Perrard, F., Deschamps, A., Tassin, C., Pisch, A.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 20-10-2003; Elsevier Science
• Subjects: Ageing; Applied sciences; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Magnesium alloys; Materials science; Metals. Metallurgy; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Precipitation; Rare earth; SAXS; Solid-phase precipitation; TEM; Rare earth; TEM; Ageing; Magnesium alloys; SAXS; Electron diffraction; Thermal ageing; Yttrium alloys; Small angle X ray scattering; Experimental study; Neodymium alloys; Precipitation hardening; Heat treatments; Phase transitions; Zirconium additions; Magnesium base alloys; Transmission electron microscopy; Rare earth: TEM
• DOI: 10.1016/S1359-6454(03)00391-4
• EISSN: 1873-2453
• ISSN: 1359-6454

Early stages of precipitation in a Mg–Y–Nd based alloy aged at 150 °C have been studied using TEM and small angle X-ray scattering (SAXS). The former brings information concerning nature, morphology and size of precipitates, and the latter adds qualitative and quantitative information concerning populations of precipitates in terms of size and volume fraction. Precipitation at 150 °C involves formation of DO
19 monoplanar precipitates, which further develop into the β″ and β′ phases having platelet and globular morphologies, respectively. TEM observations on samples aged at 150 °C reveal the formation mechanism of the bco-β′ structure by the ordering of monoplanar DO
19-β″ precipitates. Additional examinations at 250 °C revealed the DO
19-β″→bco-β′ transformation, as well as β
1 precipitates. Estimation of the volume fraction deduced from SAXS is discussed on the basis of the TEM results.