Morphology and properties of Mg₂Si and Mg₂(Si_xSn_1−x) reinforcements in magnesium alloys

ABSTRACT

In this paper, the effects of Sr, Sb, Sr+Sb and Sn on Mg₂Si reinforcement phases in an Mg–Al–Zn–Si alloy are studied, and the structures and characteristics of Mg₂(Si_xSn_1−x) phases are analysed with first-principle calculations. The results show that the coarse eutectic Mg₂Si can be refined by modifying processes with Sr, Sb, and their combination. When alloying with Sn, a new reinforcement phase Mg₂(Si_xSn_1−x) forms by a substitution reaction, instead of Mg₂Si. Calculations indicate that Mg₂(Si_xSn_1−x) has a certain percentage of covalent bonds, which ensure it has sufficient hardness to act as a reinforcement phase. Calculated results for physical parameters, such as the bulk modulus and shear modulus, indicate that an Mg₂(Si_xSn_1−x) intermetallic exhibits greater ductility than Mg₂Si.

Highlights

• The coarse eutectic Mg₂Si can be refined by modifying processes.

• A new phase Mg₂(Si_xSn_1−x) forms by substitution reaction during solidification.

• Mg₂(Si_xSn_1−x) has certain covalent bound percentage.

• Mg₂(Si_xSn_1−x) has better plasticity than that of Mg₂Si.

KEYWORDS:

• Mg–Al–Zn–Si alloy
• Mg₂Si
• Mg₂(Si_xSn_1−x)
• first-principle calculation

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The project was financially supported by the National Natural Science Foundation of China (Grant No. 51571086) and the Doctoral Foundation of Henan Polytechnic University, China (Grant No. B2010-20).