The effect of Ti alloying on the mechanical properties and microstructure of a Zn-Al-Cu-Mg alloy

Abstract

The effect of Ti additions (0.01-0.20 wt.%) on the hardness, ultimate tensile strength, impact strength and creep properties of the gravity-cast Zn-Al-Cu-Mg alloy ZA-8 has been investigated. The Ti additions have no significant effect on the hardness. The ultimate tensile strength of the standard ZA-8 alloy has not been changed significantly with Ti additions up to 0.15 wt.% and then decreased with further increase in Ti content. The impact strength shows a maximum around 0.05-0.15 wt.% Ti. The lowest creep resistance is obtained at 0.01 wt.% Ti, and the highest value of creep resistance is reached for 0.20 wt.% Ti. Metallographic studies indicated that the addition of Ti has a profound effect on the microstructure. Also, Ti forms a complex-shaped intermetallic compound which was identified as TiZn15 by X-ray diffraction. It is suggested that the TiZn15 particles cause the increase in creep resistance and decrease in tensile strength.