Fe_3Al基金属間化合物合金の引張特性に及ぼすZrおよびNb添加の効果(力学特性)  [in Japanese] The Effect of Zr and Nb Addition on Tensile Property of Fe_3Al-based Intermetallic Alloys(Mechanical Properties)  [in Japanese]

Several kinds of Zr and/or Nb added Fe_3Al based intermetallic alloys (i.e., Fe_3Al-Zr, Fe_3Al-Nb and Fe_3Al-Zr-Nb) were arc-melted, homogenized, hot-rolled and then annealed to evaluate microstructure and tensile property at room temperature as well as at a high temperature (873K). After annealing above 1073K, the rolled alloys exhibited a recrystallized microstructure containing coarse Laves phase particles, except for the Nb-added alloy with a minor content of Nb, which showed a single phase microstructure. For the as hot-rolled and recrystallized specimens, relatively high tensile elongation as well as high tensile strength was observed at room temperature in the Zr-added alloys in comparison with those in the Nb-added alloys. Additionally, fracture mode of the Zr-added alloys exhibited intergranular fracture whereas that of the Nb-added alloys showed transgranular cleavage fracture. The recrystallized specimens except for the Nb-added alloys with a minor amount of Nb also showed relatively high tensile strength and elongation at high temperature (873K). These results suggest that tensile duetility as well as strength of Fe_3Al-based alloys can be improved by introduction of the Laves phase dispersions. The mechanism responsible for the observed improved ductility (and strength) was discussed in association with the existence of coarse second phase particles.