Abstract
To further improve the mechanical properties of Al-Si alloys. The phase, microstructure and mechanical properties of Al2O3/Al-20Si composites under different pressures were studied. The results show that the phase of Al2O3/Al-20Si composites are composed of α-Al phase, β-Si phase and Al2O3. Under the condition of hot-pressing sintering (0.02 GPa), a large number of Si phases with irregular shape and sharp angle are distributed on the α-Al matrix. Under high pressure solidification, the growth of primary Si phase is inhibited and the eutectic Si is spheroidized obviously. The microhardness of Al2O3/Al-20Si composite increases from 102.5 HV0.05 at 0.02 GPa to 156.4 HV0.05 at 4 GPa, which increases by 52.6%. The compressive strength increased from 381.5 MPa at 0.02 GPa to 469.1 MPa at 4 GPa, increasing by 23%. With the increase of solidification pressure, the fracture mechanism changes from cleavage fracture to quasi cleavage fracture.
Highlights
High silicon (20–26%) aluminum alloy has the characteristics of low density, low thermal expansion coefficient, good wear resistance and excellent comprehensive mechanical properties, so it is often used as a matrix alloy in aerospace, automobile, ship, electronic packaging fields [1,2]
The results show that the microstructure of the alloy is refined obviously with the increase of GPa high pressure
It shows that the Al2 O3 /Al20Si composite consists of α-Al phase, β-Si phase and Al2 O3 strengthening phase, and no new phase is produced during high pressure solidification
Summary
High silicon (20–26%) aluminum alloy has the characteristics of low density, low thermal expansion coefficient, good wear resistance and excellent comprehensive mechanical properties, so it is often used as a matrix alloy in aerospace, automobile, ship, electronic packaging fields [1,2]. The higher the silicon content, the better the wear resistance and heat resistance of Al-Si alloy, and the lower the coefficient of thermal expansion. Due to the coarse size and irregular shape of primary phase Si, it is easy to be cracked during the process of service, and the stress concentration exists near the sharp angle, which becomes the source of cracks. It is still of great significance to improve the comprehensive mechanical properties of high silicon aluminum alloy by changing the primary Si phase [5]
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