Overaged Samples and Growth of Eutectics Mg-6Gd-3.7Nd Based Alloys

Abstract:

The eutectic structure in Mg-6Gd-3.7Nd based alloy was characterized to be result of a 'quasibinary eutectic reaction' L→ α-Mg + β-Mg₅RE. The ST temperature applied was apparently sufficient to melt the GB regions of the as-cast Mg-Gd-Nd based alloy, and transform the eutectic structures to a globular liquid phase enriched with RE elements. High supersaturation of Mg matrix by rare earth (RE) elements after quenching of solution treated Mg-Gd-Nd alloy provides sequential precipitation of different metastable phases: α-Mg (S.S.S.S.) → β'' (Mg₃RE, DO₁₉)→ β' (Mg₇RE, BCO) → β₁ (Mg₃RE, FCC) → β (Mg₅RE, FCC). The stable β precipitates grew from the eutectic structure in the form of needle-like precipitates. These needles seem to be a continuation of the β phase presented in the eutectic structure. These β precipitates grow at the expense of smaller β₁ and β precipitates presented in the α-Mg matrix. The combination of HRTEM, TEM with SAED and JEMS simulation was carried out to characterize the nanometer-scale precipitates. Microhardness measurements were performed to reveal the effect of precipitation on the mechanical properties of the alloys.

• Periodical: Applied Mechanics and Materials (Volumes 764-765)
• Pages: 76-81
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.764-765.76
• Online since: May 2015
• Authors: Suzan Abd El Majid, Menachem Bamberger, Alexander Katsman
• Keywords: Eutectic, Mechanical Property, Mg-Gd-Nd Alloys, Microstructure, Precipitation

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