The room temperature (RT) ductility of ferritic Fe–Al–Ni-based alloys containing B2-type NiAl precipitates was improved by the refinement of the matrix. The microstructure and tensile properties of Fe–Al–Ni–Cr–Mo–Mn alloys after annealing at 1223 K followed by air cooling were investigated focusing on Mn content. The matrix of the alloy containing 4 at% Mn consists of coarse equiaxed α (bcc) grains and fine grain regions composed of the α and γ (fcc) grains. Fine grain regions are formed through the phase transformation between the α and γ phases during annealing and air cooling. In the heat treatment process, the precipitation of (FeCr)₂Mo Laves phase is effective in the refinement of the matrix grains due to grain boundary pinning effect. The alloy with fine grain regions in the matrix exhibits not only large elongation (approximately 14.7%) at RT but also high strength, compared with modified 9Cr-1Mo and 316 stainless steels in the temperature range from RT to 973 K. The fine grain regions which are fractured by ductile fracture mode are responsible for the large ductility of the alloy at RT. Moreover, the high strength of the alloy at high temperatures is attributed to the high stability of the NiAl precipitates at 973 K.

通过基体的细化，改善了含有B2型NiAl沉淀物的铁素体Fe-Al-Ni基合金的室温（RT）延展性。研究了Fe-Al-Ni-Cr-Mo-Mn合金在1223 K退火然后空冷后的显微组织和拉伸性能，重点研究了Mn含量。含有4 at％Mn的合金基体由粗等轴晶α（bcc）晶粒和由α和γ（fcc）晶粒组成的细晶粒区域组成。在退火和空冷过程中，通过α和γ相之间的相变形成细晶粒区域。在热处理过程中，（FeCr）₂的沉淀由于晶界钉扎效应，Mo Laves相可有效地细化基体晶粒。与改性的9Cr-1Mo和316不锈钢在室温至973 K的温度范围内相比，基体中具有细晶粒区域的合金不仅在室温下表现出大的伸长率（约14.7％），而且还具有高强度。通过延性断裂模式断裂的合金是造成合金在室温下大延展性的原因。此外，合金在高温下的高强度归因于973 K下NiAl析出物的高稳定性。