EFFECT OF ADDITION OF HAFNIUM (HF) ON THE MECHANICAL BEHAVIOR AND WEAR RESISTANCE OF ZINC-ALUMINUM ALLOY5, ZA5

摘要

Zinc Aluminum alloys in general are versatile materials which are widely used in industrial and engineering applications due to their good resistance to wear and corrosion. These alloys solidify in large grain dendritic structure which negatively affects their mechanical strength and surface quality. Therefore, they are normally grain refined by some rare earth elements e.g. Ti, Ti+B or Zr. The effect addition of these elements on the microstructure, mechanical characteristics, impact strength, wear resistance and fatigue life has been reviewed and presented by the first author in FAEM-2006. To the best of the author's knowledge the effect of Hafnium, Hf, on the metallurgical and mechanical behavior have not been investigated. In this paper, the effect of addition of Hafnium (Hf) at different weight percentages ranging from 0.02% to 0.12% to ZA5 as a grain refiner on its micro structure, hardness, mechanical behavior and wear resistance, is presented and discussed. The effect of addition of Hf at a rate of (0.02%, and 0.12%) to ZA5 alloy resulted in refining the dendritic structure of the base material, and improved its micro hardness. The effect of addition of Hf at a rate of (0.10% and 0.12%) to ZA5 resulted in slight improvement of its mechanical behavior by 0.4% and 0.2% respectively. Regarding the effect of addition of Hf on the wear resistance of this alloy, it was found that improvement has occurred only at high load and speed, namely at 20 N and 153.467 m/min speed and addition of (0.10% Hf) to ZA5 alloy resulted in the best wear resistance as compared to other added percentages.