부산대학교 도서관

The effects of Ti and La additions on the microstructures and mechanical properties of B-refined and Sr-modifi ed Al–11Sialloys were investigated in the present work. The interactions among Ti, La, B and Sr elements were discussed employingmicrostructure observation, thermal analysis and tensile test, respectively. It was found that the addition of 0.05 wt% Binduces a transformation of eutectic Si from fi nely fi brous to coarsely plate-like morphology in the Al–11Si alloy with 0.02wt%Sr modifi cation, owing to the poisoning of IIT mechanism, and the eutectic Si grows only with TPRE mechanism. Bothtitanium and lanthanum can neutralize the co-poisoning effect between Sr and B in the Al–11Si alloy, but the neutralizingeffect of La is dependent on the addition sequence. The combinative addition of La and B elements promotes the effectiverefi nement of α-Al grains, but an inhomogeneous modifi cation of eutectic Si phases is also observed, leading to a slightlydecrease in the elongation.