Ti alloying effects on the microstructure, mechanical properties and damping capacity of Al-Zn eutectoid damping alloys

Abstract

Four Al-Zn eutectoid damping alloys with nominal compositions of 50Al-(49.9-x) Zn-xTi-0.1Ce (x=0, 0.5, 1 and 2 respectively) (atomic percentages, at%) were prepared by hot extrusion following the resistance and induction melting and homogenization. The effects of Ti content on the microstructure, mechanical properties and damping capacity of Al-Zn eutectoid damping alloys were investigated. The results show that the eutectoid structure in the alloy is refined first and then coarsened with increase in Ti content (1Ti alloy has the finest eutectoid structure), and a small amount of (Al, Zn)3Ti intermetallic blocks are observed in the 2Ti alloy. There exist two types of regions for the eutectoid structures in the four alloys, region Ⅰ has nearly granular morphology and relatively large phase sizes, and region Ⅱ has very fine lamellar structure (the lamellar spacing is only 50–80 nm in 1Ti alloy). With the increase of Ti content, the area percentage of region II exhibits an increasing trend. The tensile property of the alloy is ameliorated by Ti addition, and the tensile strength increases first and then decreases with the increase of Ti content. In particular, 1Ti alloy has a high tensile strength of up to 390 MPa, which is increased by 49.43% compared to that of 0Ti one. The damping capacity of the alloys is improved by proper addition of Ti (tan δ values of 0.5Ti and 1Ti alloys increase by 78.26% and 26.09%, compared to that of 0Ti one), while is not changed obviously by further addition of Ti (up to 2 at%).