查看更多>>摘要：Al-5Ti-1B is commonly added to refine the grain size of Al alloys. However, its presence affects the type, size, morphology, and formation sequence of Fe-rich intermetallic phases. The underlying nucleation and growth mechanisms of Fe-rich phases under the influence of Al-Ti-B during the solidification of Al-Cu-Fe(-Si) alloys has been systematically studied by thermodynamic calculation and experimental techniques: scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), focused ion beam (FIB), transmission electron microscopy (TEM), and in-situ synchrotron X-ray radiography. The SEM and in-situ synchrotron X-ray radiography experiments revealed that the Al-Ti-B addition significantly reduce the size and number of primary Al-3(CuFe) phases, and refine the size of alpha-Fe in Al-Cu-Fe-Si alloy without changing their type. This was caused by Ti solute atoms in Al melts, which limits the nucleation and growth of primary Al-3(CuFe) phases during solidification. The FIB and TEM results showed that the priorly formed TiB2 particles were nucleate sites for Al-6(CuFe) phase and alpha-Fe phase in Al-Cu-Fe alloy and Al-Cu-Fe-Si alloy, respectively. The Edge-to-Edge model and the orientation relationship further confirmed the experimental results. This study may provide fundamental understanding about the influence of Al-Ti-B on the nucleation and growth of Fe-rich phases.
NSTL
Elsevier