Silicon Nitride Whisker-Reinforced Aluminum Matrix Composites: Twinning and Precipitation Behavior
oleh: Shoujiang Qu, Aihan Feng, Lin Geng, Jun Shen, Daolun Chen
| Format: | Article |
|---|---|
| Diterbitkan: | MDPI AG 2020-03-01 |
Deskripsi
Aluminum composites reinforced with ceramic whiskers exhibited a unique combination of high specific strength and superior specific modulus. A 20 vol.% Si<sub>3</sub>N<sub>4w</sub>/Al-11.5Si-1.0Mg-0.5Cu-0.5Ni (wt.%) composite was fabricated via squeeze casting in the present study. It was observed that the addition of silicon nitride (Si<sub>3</sub>N<sub>4</sub>) whiskers in the Al-Si cast alloy promoted extensive twinning in the eutectic silicon particles due to a coupled role of thermal stresses between the matrix and silicon and residual stresses present in the composite. Double aging peaks were present in the age-hardening curves. The precipitation mechanism involved the formation of Mg<sub>2</sub>Si and Al<sub>2</sub>CuMg phases. The presence of Si<sub>3</sub>N<sub>4</sub> whiskers in the composite retarded the nucleation process of Mg<sub>2</sub>Si precipitate while enhancing its growth rate.