Microstructure And Properties Of SiCp/Al Sintered By High Pressure

In the study,we get the SiCp/Al composites by high pressure sintering,the experiment conditions were as follows:aluminum silicon powders as matrix, the mass ratio of them was 4:1, the volume fraction of SiC reinforcement were 35%,40%,45% respectively, the sintering pressure were 2GPa,4GPa,6GPa.For comparation, we got the same volume fraction of SiC composites under the pressure of 30MPa.We investigated the influence of different pressures and different SiC volume fractions on the phase composition and microstructure analysis, the properties of the composites were analyzed too.Hot pressure sintering as well as high pressure of 2GPa, the phase compositions wereβ-Si+(α-Al+β-Si)eutectic.when the pressure was 4GPa,6GPa, the phase composites wereα-Al+(α-Al+β-Si)eutectic.Most of the eutectic silicon phase grow around the SiC particles, and the interfacial bonding betweenn silicon phase and SiCp was strong,at the interface we didn't find the harmful phase Al4C3. As the sintering pressure increased, the matrix were refined,β-Si phase gradually disappeared and primary-Al gradually increased. The diffraction peaks of aluminum moved left, and the lattice constant becoming bigger when the pressure increased.Under the same pressure, the eutectic structure were refined with the increase of SiCp volume fraction. Compared high pressure sintering with hot pressure sintering, the size of primary Si phase was significantly smaller, eutectic silicon presents fibrous, indicating pressure has a significant metamorphism on the eutectic silicon.The density of the composites increase as the pressure increased, at 4GPa reached maximum;the hardness of the composites increase as the pressure increases. For the same composition of materials,the compressive strength of materials prepared by high pressure sintering was ranged from 565MPa to 700 MPa, compared with hot pressure sintering,the average compressive strength was about 190.78% higher. The fractography showed that the composite materials prepared by the hot pressing method took place fracture in the interface junction between matrix and particulate reinforced; and under high pressure sintering,SiC and aluminum matrix composites had a strong combination, most SiC cleavage fracture occurred. Under the same pressure, density, the hardness, compressive strength of materials increased gradually. Compared high pressure sintering with hot pressure sintering, it increased the properties of composites.