Grain Refinement of Al Cast by Al5CuTi2, Al22Fe3Ti8 and Al67Ni8Ti25 Intermetallic Compounds with L12 Structure

Abstract

It is known that alloying with a certain amount of transition element such as Cr, Mn, Fe, Co, Ni and Cu causes the transformation from the D022 type tetragonal structure of Al3Ti into high-symmetry L12 cubic structure. The lattice constants of Al5CuTi2, Al22Fe3Ti8 and Al67Ni8Ti25 intermetallic compounds with L12 structure are a = 0.3927 nm, a = 0.393 nm and a = 0.394 nm, respectively. Therefore, smaller disregistry values between Al and these phases can be achieved. In this study, novel refiners for Al cast containing Al5CuTi2, Al22Fe3Ti8 and Al67Ni8Ti25 intermetallic compound particles with L12 structure are fabricated by spark plasma sintering (SPS) method. Al-10vol%Al5CuTi2, Al-10vol%Al22Fe3Ti8 and Al-10vol%Al67Ni8Ti25 refiners with L12 structure particles can be successfully fabricated by the SPS method. Fabricated refiners with L12 structure are found to be effective grain refiners for pure Al, since the Al5CuTi2, Al22Fe3Ti8 and Al67Ni8Ti25 intermetallic compounds act as nuclei of Al grains in Al melts. Using heterogeneous nucleation sites with lower disregistry value, one can obtain finer grained Al casts with higher mechanical properties.