Precipitation of β-Mn in the Form of Widmanstätten Side-Plates in the Ferrite Matrix of an Fe–28.6 Mn–10.9 Al Alloy Steel
Year: 2025
Type: article
Abstract: The microstructural evolution and phase stability in Fe–Mn–Al alloys play a decisive role in determining their mechanical performance and potential applications. This study investigates the precipitation behavior and crystallography of the β-Mn phase in an Fe–28.6 Mn–10.9 Al (wt.%) alloy subjected to annealing at 1100 °C, followed by water quenching and subsequent isothermal holding at temperatures between 500 °C and 900 °C for 20 h. Microstructural analysis using X-ray diffraction, optical and electron microscopy revealed a single body-centered cubic (BCC) ferritic matrix above 850 °C and the formation of β-Mn precipitates with Widmanstätten side-plate morphology at lower temperatures. The β-Mn phase was thermally stable between ~500 °C and 850 °C, with the volume fraction increasing with temperature and reaching a maximum near 650 °C. The β-Mn precipitates coarsened progressively with increasing temperature and were found to be richer in Mn than the surrounding Fe-rich BCC matrix. Crystallographic analysis established an orientation relationship (OR) of (021¯)β // (100)α and [1¯12]β // [012]α, where // denotes nearly parallel alignment, signifying a semi-coherent interface between the two structures. These findings clarify β-Mn precipitation, its interfacial relationship with ferrite, and its thermal stability in high-Mn Fe–Mn–Al alloys, offering guidance for microstructural design in next-generation lightweight steels.
Source: Materials
DOI: 10.3390/ma19010133
Authors: Rosemary Chemeli Korir, Wei-Chun Cheng
Institution: National Taiwan University of Science and Technology
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,137
OpenAlex ID: W7117716002