The aging behaviour of a Mg-10Gd-3Y-1.0Zn-0.5Zr (wt.%) alloy with long-period stacking ordered phase at 275°C

ABSTRACT

We investigated the aging behaviour of a Mg-10Gd-3Y-1.0Zn-0.5Zr (wt.%) alloy with long-period stacking ordered (LPSO) phase at 275°C. Its peak hardness is about 116.4 HV after aging for 25 h. We unravelled the evolution of prismatic precipitates through transmission electron microscopy (TEM). The formation process is β′ (10h)→ β′ + β₁ (15 h)→ β′ + β₁ + β (≥20 h), where nano-scale ${{\text{β}}^{\mathrm{\prime }}}_{\mathrm{F}}$ phase benefits the transformation from β′ phase to β₁ phase. In addition to the stable basal LPSO structures, the coexistence and competition balance between the prismatic β′, β₁ and β phases synergistically contribute to the high hardness of the aged alloy. The number density of the prismatic precipitates is at the magnitude of 10²⁰/m³. These prismatic precipitates during aging largely determine the hardness of the Mg alloys. The interaction between precipitates and stacking faults brings good compression property.

KEYWORDS:

• Magnesium alloy
• LPSO structure
• aging
• hardness
• precipitation

Acknowledgment

The authors wish to express their appreciation to Prof. Y. J. Wu of Shanghai Jiao Tong University for her help with sample fabrication.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work is supported by the National Natural Science Foundation of China [grant number 51871222 and 52171021], Liaoning Provincial Natural Science Foundation [2019-MS-335] and Guangxi Science and Technology Base and Talents Special Project [Guike AD20297034].