Effects of other elements on grain refining of cast structure of Aluminum by the addition of Ti or Ti-B

Abstract

Many studies have already been made on grain refining of cast structure of aluminum, and Ti and Ti-B have widely been used as the most effective grain refiners.However, few investigations were made on the effects of the presence of small amounts of other elements on grain refining of aluminum by these refiners.Accordingly, these studies were undertaken to achieve the effects of Fe, Si, Cu, Mg, Zn, or Zr on grain refining of aluminum by the addition of Ti or Ti-B.The results obtained were as follows:(1) The effects of grain refining by Ti and Ti-B were enhanced by the presence of Fe, Si, Cu, Mg, Zn or Zr. Among these, Si was the most effective, and Mg was the second.(2) A relation was given between the amounts of Ti and Si or between Ti and Mg required for the grain refining of cast structure of aluminum.For instance, grain refining of 99.99% Al was markedly enhanced by the presence of Si (over 0.65%) or Mg (over 0.8%) for 0.01% of Ti, and it was also enhanced by the presence of Si (over 0.05%) or Mg (0.1%) for 0.05% of Ti.(3) The effects of grain refining by the addition of Ti alone were remarkably weakened when casting temperature was high, whereas the effects by the addition of Ti-B less depended upon the temperature. When Si or Mg was added together with Ti, the results were almost the same as that of Ti alone; but the critical casting temperature, at which a conspicuous weakening of grain refining was seen, was higher than that of Ti alone.