The effects of mold material on the mechanical and microstructuralproperties of 7075 aluminum alloy in centrifugal casting

In this study, the Al 7075 alloy, known for its high strength and low density and widely used in aerospace, automotive, and defense industries, was cast using four different mold materials: metal, ceramic, sand, and plaster. The aim was to examine the effect of cooling rate on microstructure and mechanical properties. The metal mold, due to its high thermal conductivity, enabled the fastest cooling, resulting in a fine-grained and dense structure. This structure led to the highest hardness, compressive strength, and wear resistance. The ceramic mold also provided relatively good performance. In contrast, the sand and plaster molds resulted in slower cooling, coarser grains, increased porosity, and lower mechanical properties. EDS analysis revealed that copper tended to concentrate at grain boundaries, while magnesium was homogeneously distributed within the matrix. XRD and DSC results showed that strengthening precipitates such as MgZn₂ and Al₂CuMg were more prominent in the metal and ceramic mold samples, indicating a greater potential for precipitation hardening. Wear tests showed the lowest friction coefficient for the metal mold, which also correlated with lower surface roughness values. These findings confirm that mold material plays a critical role not only in shaping the part but also in controlling the solidification rate, microstructural characteristics, and final mechanical performance of Al 7075 alloy.