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A study on the phase transformation of γ2-Al8Mn5 to LT-Al11Mn4 during solutionizing in AZ91 alloy
•γ2-Al8Mn5 phase transformed to LT -Al11Mn4 phase due to uphill diffusion of Al.•Shell type structure developed where LT -Al11Mn4 shell encapsulated γ2-Al8Mn5 phase.•Higher volume of LT-Al11Mn4 phase resulted in cracks in the shell.•Si, Fe and Mg content decreased in the LT-Al11Mn4 during solutioniz...
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Published in: | Journal of alloys and compounds 2021-08, Vol.873, p.1, Article 159836 |
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Main Authors: | , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Online Access: | Get full text |
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Summary: | •γ2-Al8Mn5 phase transformed to LT -Al11Mn4 phase due to uphill diffusion of Al.•Shell type structure developed where LT -Al11Mn4 shell encapsulated γ2-Al8Mn5 phase.•Higher volume of LT-Al11Mn4 phase resulted in cracks in the shell.•Si, Fe and Mg content decreased in the LT-Al11Mn4 during solutionizing.
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γ2-Al8Mn5 intermetallic particles are generally present in commercial Mg-Al-Zn alloys. The present study is concerned with the effect of solutionizing on the morphology and phase stability of the γ2-Al8Mn5 particles in an as-cast AZ91 alloy. Analysis using energy dispersive spectroscopy (EDS) and electron back scattered diffraction (EBSD) in a scanning electron microscope (SEM), transmission electron microscopy (TEM) and atom probe tomography (APT) suggests that solutionizing resulted in uphill diffusion of Al from the α-Mg matrix resulting in the phase transformation of γ2-Al8Mn5 to Low Temperature (LT) -Al11Mn4 phase. This leads to a shell type structure of LT-Al11Mn4 encapsulating γ2-Al8Mn5 and the formation of cracks in the LT-Al11Mn4 phase. These can propagate during external loading, affecting the mechanical properties. Additionally, the content of Fe and Si decreased in the LT-Al11Mn4, which could potentially decrease locally the corrosion resistance. |
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ISSN: | 0925-8388 1873-4669 |
DOI: | 10.1016/j.jallcom.2021.159836 |