STUDY OF MACROSEGREGATION EFFECTS ON THERMAL AND ELECTRICAL CHARACTERISTICS OF ALUMINUM-COPPER ALLOY

Obiekea, V.D. ; Sekunowo, I.O. ; Sobamowo, M.G. ; Adeosun, S.O. (2018)

Article

Macrosegregation phenomenon regardless of casting size often induces high partition coefficient (k) impacting adversely the thermal and electrical properties of cast binary alloy. In this study, an experimental investigation of macrosegregation propagation in aluminum-copper alloy solidification is reported. Al6wt. % Cu was produced at varied pouring heights including 100 mm, 200 mm, 300 mm, 400 mm and 500 mm. The combinations of optical, scanning electron and energy dispersive spectrometry were used to evaluate the extent of segregation in the casts while the electrical and thermal conductivity properties were determined using Wiedemann-Franz Law. Results show that the Al-Cu cast at a pouring height of 400 mm demonstrated the highest electrical and thermal conductivity of 55 %IACS and 2.1437 W/mK 10-6 respectively. This compared well with established standard values in application such as heat exchangers and electronic sensors. The occurrence of minimal macrosegregation at 400 mm pouring height may be attributed to appropriateness of melt-flow regime resulting in desirable microstructure that prevents long-range solute/solvent segregation.