Mechanism of AlP modifying the morphology of Si in Al-20Si alloys based on experimental studies and first-principles calculations

ABSTRACT

The modifying influence of aluminium phosphide to the morphology of primary Si and eutectic Si was investigated in hypereutectic Al-20Si alloys via adding Al-Cu-P master alloy (0.5, 1, 20 wt.%). Microstructural results showed when Al-Cu-P addition from 0 to 0.5%, primary Si phase decreases and eutectic Si phase size remains invariable; when addition higher than 0.5%, primary Si phase keeps invariable, eutectic Si phase size increases. To prove the nucleation effect of AlP on Si phase, interfacial properties of Si/AlP interface were investigated using first-principles calculations. Results showed the AlP(100)/Si(100) interface energy is between −1.45 J/m² and −1.38 J/m² for Al-terminated and P-terminated AlP model, both is much smaller than liquid Si/crystalline Si interface (0.34 J/m²), consolidates that AlP particles possess strong nucleation potency for Si phases. Therefore, the modifying influence of AlP to the morphology Si phase is well clarified as a function of AlP content in Al-20Si alloys. 

KEYWORDS:

• Heterogeneous nucleation
• Si/AlP interface
• first-principles calculation
• Hypereutectic al-si alloys

Acknowledgments

This study was financially supported by the Anhui Provincial Natural Science Foundation (1808085ME123, 1908085MF197), the Projects of International Cooperation and Exchanges in Anhui Provincial Key Project of Research and Development Plan (1804b06020363, 202004b11020010), Natural Science Foundation of Anhui Provincial Education Department (Grant No. KJ2020A0262).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The work was supported by the Anhui Provincial Department of Education [Grant No. KJ2020A0262]; Natural Science Foundation of Anhui Province [1908085MF197]; Natural Science Foundation of Anhui Province [1808085ME123]; Projects of International Cooperation and Exchanges in Anhui Provincial Key Project of Research and Development Plan [202004b11020010]; Projects of International Cooperation and Exchanges in Anhui Provincial Key Project of Research and Development Plan [1804b06020363].