Effects of Casting Speed and Runner Angle on Macrosegregation of Aluminium-Copper Alloy.

Abstract During the solidification of binary metal alloys, chemical heterogeneities at product scale over a long distance range (1cm-1m) develop and this has detrimental effect on the resulting mechanical properties of cast products. Macrosegregation is of great concern to alloy manufacturers and end users as this problem persist. In this study, the use of process parameters namely casting speed and runner angle to reduce macro-segregation in aluminum-copper-zinc binary alloy solidification is reported. The results from optical microscope, scanning electron microscope and energy dispersive spectrometry show that these parameters significantly influenced the development, size and volume of macro-segregation. The combination of parameters namely the pouring height between 96 mm/s, 100mm/s, and runner angles between 1200, 1500 produced less segregations with improved mechanical properties within standard specification. The tensile strength (110 MPa), modulus of elasticity (6800 MPa) and 2.5 % elongation obtained in this study are within standard (88- 124 MPa), 7100 MPa and (1-25 %) respectively for this class of alloy.