Abstract
The effect of two kinds of the finely dispersed particles with different elastic modulus from iron matrix (∈-Cu and TiN) on the low temperature ductility of ferritic iron was investigated.
∈-Cu particles were uniformly dispersed in the matrix by aging of Fe-1.83% Cu allay at 700°C for 96h, whereas TiN particles were uniformly dispersed by internal nitriding of Fe-0.1% Ti alloy at 700°C for 4h. By the presence of TiN particles, the elongation at 77K of ferritic iron with 150μ grain diameter increased by about 20%, whereas, by the presence of ∈-Cu particles, the elongation at 77K of ferritic iron with 60μ grain diameter decreased by about 20%. The reason is considered that the presence of TiN particles favors cross slip of screw dislocation around these particles which changes the deformation mode of coarser grained ferritic iron from twinned to slipped, whereas ∈-Cu particles do not work so.
