<p>The effects of trace Er addition (0–0.12 wt%) and annealing temperature (150–550 °C) on the microstructure, mechanical properties, texture, and corrosion resistance of an Al–6Mg–1Mn alloy were systematically investigated. The results demonstrate that Er significantly refines the recrystallized microstructure by the Zener pinning effect of thermally stable, nanoscale Al<sub>3</sub>Er precipitates. Quantitative Hall–Petch analysis confirms that grain refinement is the dominant strengthening mechanism, accounting for the substantial increase in yield strength, whereas the direct contribution from precipitation strengthening is minor. Furthermore, annealing at 400 °C promotes a randomization of grain orientations, transforming the strong deformation texture into a weak Cube-dominated recrystallization texture. This microstructural homogenization effectively reduces planar anisotropy and enhances the average plastic strain ratio (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">$\bar{r}$</EquationSource> <EquationSource Format="MATHML"><math> <mover accent="true"> <mrow> <mi>r</mi> </mrow> <mrow> <mo stretchy="false">¯</mo> </mrow> </mover> </math></EquationSource> </InlineEquation>). The alloy with 0.12 wt% Er annealed at 400 °C exhibits an optimal synergy of properties: The <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$\bar{r}$</EquationSource> <EquationSource Format="MATHML"><math> <mover accent="true"> <mrow> <mi>r</mi> </mrow> <mrow> <mo stretchy="false">¯</mo> </mrow> </mover> </math></EquationSource> </InlineEquation> increases from 0.759 for Er-free alloy to 0.813, and the strain hardening exponent (<InlineEquation ID="IEq3"> <EquationSource Format="TEX">$\bar{n}$</EquationSource> <EquationSource Format="MATHML"><math> <mover accent="true"> <mrow> <mi>n</mi> </mrow> <mrow> <mo stretchy="false">¯</mo> </mrow> </mover> </math></EquationSource> </InlineEquation>) reaches a peak of 0.38. The alloy simultaneously maintains a high tensile strength of 371 MPa with excellent ductility and superior corrosion resistance, evidenced by an intergranular corrosion depth of 10 μm. This study establishes that combining 0.12 wt% Er with annealing at 350–400 °C provides an optimal processing window for manufacturing high-strength, highly formable Al–Mg-Mn alloy sheets.</p>

Regulatory mechanisms of rare earth Er and annealing on corrosion resistance and formability of Al–Mg–Mn alloys

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发表日期：

2026年3月22日

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Xiangjie Wang,
Zhenyu Wu,
Lumin Gou,
Chao Zhang,
Changke Chen,
Lijuan Wang,
Zhaoxi Song,
Chengcheng Chen,
Jianzhong Cui

摘要

The effects of trace Er addition (0–0.12 wt%) and annealing temperature (150–550 °C) on the microstructure, mechanical properties, texture, and corrosion resistance of an Al–6Mg–1Mn alloy were systematically investigated. The results demonstrate that Er significantly refines the recrystallized microstructure by the Zener pinning effect of thermally stable, nanoscale Al₃Er precipitates. Quantitative Hall–Petch analysis confirms that grain refinement is the dominant strengthening mechanism, accounting for the substantial increase in yield strength, whereas the direct contribution from precipitation strengthening is minor. Furthermore, annealing at 400 °C promotes a randomization of grain orientations, transforming the strong deformation texture into a weak Cube-dominated recrystallization texture. This microstructural homogenization effectively reduces planar anisotropy and enhances the average plastic strain ratio ( $\bar{r}$ $\bar{r}$ ). The alloy with 0.12 wt% Er annealed at 400 °C exhibits an optimal synergy of properties: The $\bar{r}$ $\bar{r}$ increases from 0.759 for Er-free alloy to 0.813, and the strain hardening exponent ( $\bar{n}$ $\bar{n}$ ) reaches a peak of 0.38. The alloy simultaneously maintains a high tensile strength of 371 MPa with excellent ductility and superior corrosion resistance, evidenced by an intergranular corrosion depth of 10 μm. This study establishes that combining 0.12 wt% Er with annealing at 350–400 °C provides an optimal processing window for manufacturing high-strength, highly formable Al–Mg-Mn alloy sheets.