Abstract: The toughness of high Cr cast iron depends strongly on the amount and the distribution of carbides within interdendritic regions. Through unidirectionally solidifying samples, the effect of RB alloy was investigated on the eutectic structure of high Cr cast iron with hypoeutectic and eutectic composition. Such variables were measured as the section area of austenite dendrite arm (Dγ), the diameter of eutectic region(Ew), the spacing of carbides (FSC in the centre and FBS in the boundary of eutectic region). It is shown that the RE alloy contributes to the refining of eutectic structure and to the increase of toughness.

Key words: 高铬铸铁, 共晶组织, 稀土合金