한국주조공학회

Microstructural and corresponding hardness changes of TiFe compounds with Zr (0~6 at%) or Ce (0~3 at%) were studied using samples prepared at different solidification rates. In arc-melted (TiFe)-Zr samples, the Fe23 Zr6 and (Ti, Zr)2Fe phases formed in the TiFe matrix, while in the (TiFe)-Ce sample, the CeO2 phase formed along the grain boundary of the TiFe matrix. As the Zr content was increased, the volume fractions of the Fe23 Zr6 and (Ti, Zr)2Fe phases increased, forming a network structure. Accordingly, the hardness values of the samples also increased. With a small addition of Ce of approximately 0.1 at%, the as-cast microstructure could be effectively refined, reducing the average grain boundary diameter from ~100 µm to ~14 µm. In the rapidly solidified sample prepared through a melt-spinning method, the constituent phases were identical to those of the arc-melted samples while the grains w were refined. The microstructural changes of TiFe alloys can affect the hydrogen s storage ability as well as the mobility of the hydrogen atoms in the alloys.