Influence of Cu content on interfacial structure and mechanical properties of 3Al₂O₃2SiO₂ fiber reinforced Al matrix composites

In this paper, pure aluminium and Al-Cu (1%, 3% and 5% in mass fraction) alloy matrix composites reinforced with 35vol% 3Al₂O ₃2SiO₂ short fibers were fabricated by a squeeze-casting technique. Interfacial structure and distribution of element of the composites were investigated by means of SEM, EPMA and TEM. The experimental results indicated that when pure aluminium was used as matrix, the interface was slick and chemical reaction occurred at the interface between amorphous SiO ₂ and matrix Al. When Cu element was added into the Al matrix alloy, the amorphous SiO₂ on the fiber surface remained. Further more, with the increase of Cu element, the amount of the retained amorphous SiO₂ increased. The interfacial reaction was inhibited due to the Cu element diffusion and enrichment towards the short fiber surface. SEM observation showed that large amount of fiber was drawn out from the matrix and some of them have been ruptured. Tensile test showed that the tensile strength of the 35vol% 3 Al₂O₃2SiO_2sf/Al-Cu composite increased with the increasing of Cu content as compared with the Al₂O_3f/pure Al composite, the increment of the fracture strength of 3Al₂O ₃2SiO_2sf/Al-Cu composite were 102%, 146% and 171%, respectively.