Effects of Bi Addition on Si Features, Tensile Properties and Wear Resistance of Hypereutectic Al-15Si Alloy

Abstract

Bismuth (Bi) alloying in Aluminum (Al) alloys is considered of importance in special applications requiring improvements in the alloy machining. Despite that, the influence of Bi either on evolution of the solidification or on resulting microstructure of hypereutectic Al-Si alloys is still to be determined. The present research work is devoted to these requirements. In the present study, Al-15wt.% Si hypereutectic alloy is modified with 1.0 wt.% Bi. The effects of this addition on the morphology of the phases forming the microstructure and on the tensile/wear properties are investigated. Various samples characterized by distinct cooling rates are generated by transient directional solidification of the ternary Al-Si-Bi alloy. Microstructure is examined by optical microscopy and scanning electron microscopy (SEM) analyses, segregation by energy-dispersive X-ray spectroscopy (EDS) whereas wear and tensile properties have been characterized by standardized tests. The experimental variations of the eutectic spacing are compared to each other based on their trends. It is found that the addition of minor Bi content (~1 wt. %) permitted tensile strength and ductility of 195 MPa and 14%. Furthermore, wear resistance is improved by up to 20% due to the Bi addition. The reasons for that will be outlined.

Effect of antimony addition on the microstructure modification and properties evolution of hypereutectic Al-Si-Zr alloy

“…Up to now, there has been no report on the influence of different Sb additions on the microstructure and properties of hypereutectic Al-Si alloy with 0.3 % Zr content. The study of Cleiton Luiz Pereira et al [40] demonstrates that the tensile properties of Al-15Si alloy with 1 % Sb can be improved. The optimum addition amount of Sb in Al-20Si-0.3Zr is not clear.…”