چكيده به لاتين
Bimetals are new materials which are made by combining two different alloys with different mechanical, chemical, and physical properties in order to achieve better properties than the individual metals. Copper alloys have relatively high thermal and electrical conduction properties; and, also titanium alloys are broadly adopted due to their high strength-to-weight ratio, excellent corrosion resistance, specific thermal stability, and considerable impact resistance. On the other hand, each of these alloys are faced with certain limits in their application, including large weight and high production costs. In this study, the interfaces of A356/Brass, A356/Cu, and A356/Ti bimetals have been investigated. These bimetals were produced through compound casting process. Liquid A356 aluminum alloy was cast with three volume ratios of 5, 10, and 15 at two temperatures of 700 oC and 750 oC, around cores from the named materials. The diameter was 10 mm, and the height was 220 mm. Studying the bimetals with brass cores revealed that at a pouring temperature of 700 oC, the diffusion zone at the boundary of the two metals has formed locally and discontinuously for all of the three volume ratios. As the pouring temperature increases to 750 oC, continuity and thickness of the diffusion layers increase. EDS analysis of the interface zones from the core outwards respectively shows CuZn, Cu4Zn, Al2Cu, eutectic layer, and eutectic layer + matrix dendrite. About the copper-core bimetal, the maximum thickness of the interface layer is related to the sample prepared at 750 oC with a liquid volume ratio of 10. Temperature increase in this sample resulted in the formation and thickness increase of the diffusion zones and the interface. The formed layers in this sample are Al2Cu5, AlCu, and Al2Cu. Temperature increase in this bimetal results in an increase in the pores and the presence of Al2O3 oxide. Regarding the thickness of the diffusion zones and the absence of the cast defects, the volume ratio of liquid to the sample core being 10 yields optimum results. The formed layers in the titanium-core bimetal are localized and include TiSi2 and Al3Ti. However, the interface zone is not similar to the other two samples in regards with morphology and structure.
