Effect of combined addition of Al-Ti-B ribbon and Zr element on the microstructure, mechanical and damping properties of ZA22 alloy

A novel Al-5Ti-1B ribbon was prepared and used as inoculant to refine the grains of Zn-Al eutectoid (ZA22) alloy with the aim to significantly enhance the mechanical properties while remaining the high damping capacity. It was found that compared with the commercial A1-5Ti-1B rod the present ribbon had better refining effect on the ZA22 alloy due to its finer and more uniformly distributed TiB2 and L1(2)-A1(3)Ti particles formed during rapid cooling process. It has been confirmed that both of the two kinds of particles could act as effective heterogeneous nucleation sites of alpha-Al phase, and then led to the refinement of alpha-Al grains. The combined addition of Al-5Ti-1B ribbon and Zr element could achieve the best refining effect because Zr could further promote the heterogeneous nucleation and hinder the growth of a-Al grains. Properties tests illustrated that with the decrease of average grain size, the tensile strength, elongation and hardness of the ZA22 alloy increased obviously because of the fine-grain strengthening and dispersion strengthening effects, while the damping showed different variation patterns within different temperature regions, which has been ascribed to the synthetic effect of two opposite influencing factors.