The grain refinement behavior of TiB2 particles prepared with in situ technology

Abstract: The grain-refining behavior of TiB2 particles was investigated by the method of adding Al–4B master alloy into the melt of electrolytic low-titanium aluminum (ELTA). The results indicate that TiB2 particles will be formed when the Al–4B master alloy is added into the melt of ELTA. These TiB2 particles are produced by in situ technology, thus their surface properties are preserved and do not alter. At the bottom of the melt, the TiB2 particles are pushed to the grain boundaries because of the absence of enough titanium atoms, which indicates that TiB2 particles alone are not potent nuclei of α-Al. Though some TiB2 particles settle down at the bottom, there are still numbers of fine TiB2 particles suspended. These TiB2 particles, together with the titanium atoms left, will form much more heterogeneous nucleation sites during the solidification of the melt, resulting in the grain-refining efficiency of the ELTA with Al–4B addition being improved obviously. To investigate the grain-refining mechanism of aluminum, this method has its advantages in comparison with that of adding synthetic TiB2 particles into the melt of aluminum. [Copyright &y& Elsevier]