Microstructural Analysis of Cast and Heat-Treated Mg–3.2Ce–2Mn Alloy

• Published in: Russian journal of non-ferrous metals 2021-05, Vol.62 (3), p.311-319
• Main Authors: Sang, H., Shah, S. S. A., Sun, B. L., Khan, A., Jing, H. M., Peng, G. S., Song, G. S.
• Format: Article
• Language: English
• Subjects: Atomic radius; Chemistry and Materials Science; Electron microscopy; Electron probe microanalysis; Enthalpy; Eutectic alloys; Heat treatment; Intermetallic compounds; Magnesium; Manganese; Materials Science; Mathematical analysis; Metallic Materials; Microscopy; Microstructural analysis; Physical Metallurgy and Heat Treatment; Precipitates
• ISSN: 1067-8212; 1934-970X
• DOI: 10.3103/S1067821221030135

A distingtive eutectic structure with Mn particles observed in as-cast Mg–3.2Ce–2Mn (wt %) alloy was investigated in detail in the present study. Three phases (α-Mg + Mn + Mg 12 Ce) in the eutectic region were identified by a combination of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The intermetallic compound Mg 12 Ce-type composition was determined to be Mg 11.4 Ce with a solubility of 0.7 at % Mn by electron probe microanalysis (EPMA). The enthalpy of formation Δ H of Mg–Ce, Mg–Mn, and Mn–Ce was also calculated with the Miedema model and applied to explain the formation mechanism of the Mg 12 Ce-type intermetallic compound in the alloy. While, after heating at 350°C for 72 hours, thin rod-like linear and intersecting Mn precipitates were observed. Since they were originated from the matrix; their linear structure could be attributed to the coherent interface between the matrix and precipitation. In addition, Mn particles associated with the Mg 12 Ce-type intermetallic compound also appeared due to the atomic radius mismatch and enthalpy of formation.