Effects of macrosegregation on mechanical and tribological properties of squeeze casting immiscible bearing alloys

The macrosegregation behaviors of Al-Sn-Cu ternary immiscible alloy castings and their effects on mechanical and tribological properties were investigated. The results demonstrate that Sn and Cu segregate in the casting simultaneously, and the mass fraction of the two elements has a “U” shaped distribution. Significantly, positive and negative segregation occur in the casting, with positive segregation appearing on the top and lower surfaces and negative segregation on the remaining surfaces, with the 1/2 surface (hot node location) having the highest degree of negative segregation. Furthermore, the results of Vickers hardness, tensile strength, and elongation show that Sn and Cu cooperatively affect the mechanical properties of castings. The higher the mass fraction of Sn and Cu elements, the higher the hardness, the greater the tensile strength, and the better the elongation. The findings of the step-by-step loading tests demonstrate that the segregation of Sn and Cu significantly impacts the tribological characteristics of the castings. The higher the mass fraction of Sn and Cu on the sample surface, the better the tribological characteristics.