Effect of Tantalum (Ta) Addition to Zinc-Aluminum Alloy 5 (ZA5) on its Microstructure and Fatigue Life

Abstract

Due to their resistance to wear and corrosion, the use of Zinc-Aluminum (Zn-Al) alloys in general and Zinc-Aluminum 5 (ZA5) alloys, in particular, have spread in the last two decades in industrial applications. These alloys normally solidify in a coarse dendritic structure which affects their surface quality and mechanical behavior. Therefore, their structure is normally refined by rare earth materials, such as Titanium (Ti), Titanium-Boron (Ti-B) or zirconium (Zr). In this research, the effect of adding Tantalum (Ta) to ZA5, at the following percentages: 0.02%, 0.04%, 0.06%, 0.08%, and 0.10%, on its microstructure and fatigue life is investigated. The results of this work revealed, within the experimental range, that the addition of Ta as a grain refiner at all rates could change the coarse dendritic structure of ZA5 into a fine nodular one. It was also found that adding Ta at 0.04% to ZA5 increased its fatigue life at a stress level of 160 MPa. However, adding Ta at a rate percentage higher than 0.04% and at stress level exceeding 160 MPa resulted in deterioration of its fatigue life.