研究了中频感应炉熔炼、金属型冷却制备的Fe_3Al铸态及热处理后的组织、力学性能和冲击断裂行为.结果表明:合金的铸态组织为等轴晶,平均晶粒尺寸约为100μm左右;合金经1000℃,15h均匀化退火+炉冷+600℃,1h中温回火+油淬热处理后,晶界得到了细化,晶内和晶界上析出了弥散分布的第二相,合金晶粒尺寸有所长大;XRD及EPMA点扫描分析综合得出弥散相的主要成分为Fe_2AlCr,基体主要相组成为Fe_2AlCr、Fe_3Al、FeAl,晶界处主要相组成为Fe_2AlCr和FeCr;热处理后合金的σ_b提高了46MPa,HRC由铸态时的22.5提高到了26.8,但合金的冲击韧性有所下降;铸态时合金的断裂方式主要以沿晶断裂为主,热处理后合金断口呈沿晶+穿晶的混合型断裂特征.
Fe_3Al alloy was prepared in a medium frequency induction furnace and solidified in a permanent mould. The microstructure, mechanical properties and impact fracture of Fe_3Al alloy were studied. The microstructure of the as-cast alloy was characterized by equiaxed grains with an average grain size of about 100μm. After having been heat treated (1000℃/15h homogenizing annealing + furnace cooling + 600℃/1h tempering + oil quenching), the grain boundaries were refined and the grain size increased. The dispersive second phase was precipitated within the grains and on the grain boundaries. The results of XRD and EPMA show that: the dispersive phase is mostly Fe_2 AlCr; the matrix phase is composed of Fe_2 AlCr, Fe_3 Al and FeAl, and the grain boundary phases are Fe_2AlCr and FeCr. Due to the heat treatment, the tensile strength of the alloy increases by 46 Mpa and the hardness increases slightly, but the impact toughness decreases. The impact fracture transforms from intercrystalline fracture to intercrystallin + transcrystalline mixed fracture after the heat treatment.
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