Effect of Zr Addition on the Mechanical Behavior, Ductility and Wear Resistance of Aluminum Grain Refined by Titanium

Abstract

Aluminum and its alloys are the second most commonly used metal for a variety of engineering applications. They solidify in columnar structure with large grain size which normally affects their mechanical behavior and surface quality. It is now becoming customary in aluminum foundry to grain refine their structure by adding either titanium or titanium + boron to their melt before solidification. In this paper, the effect of addition of Ti on the mechanical properties, ductility and wear resistance of commercially pure aluminum is investigated. Titanium was added at a level of 0.15 % wt. This ratio corresponds to the peritictic limit on the Al-Ti phase diagram and is normally used for grain refining of aluminum. It was found that addition of Ti at this level resulted in grain refinement of aluminum structure whereas addition of Zr alone resulted in grain coarsening of Al structure while it resulted in grain refinement when it is added in the presence of Ti. Regarding the effect of Zr on the wear resistance of aluminum it was found that at small loads and speeds addition of Ti or Zr or both together resulted in deterioration of its wear resistance whereas at higher loads and speeds resulted in pronounced improvement of its wear resistance.