一、序言 由于长程有序金属间化合物Fe_3Al和FeAl具有良好 的高温抗氧化性、低密度和低成本等特性,而受到世界各 国材料科学工作者的重视。但是,它的室温脆性是工程材 料应用的主要障碍。人们试图通过合金化来提高这两种 化合物的塑性。以往的研究表明,少量Cr可以明显提高 变形Fe_3Al合金的室温塑性;但我们的实验表明,Fe_3Al 中加入2.5at％Cr并没有使铸态室温拉伸塑性明显提 高。微量硼可使FeAl拉伸断口由沿晶变为穿晶特征,塑 性提高,而延伸率的绝对值仍然不高。也有人用快速 凝固法来提高塑性,但工艺复杂,成本太高,难于实用化。 提高多晶Fe_3Al和FeAl塑性的简单可行的方法仍然是合 金化。因此,有必要进一步研究利用合金化来改善塑性。 受高温合金合金化的启示,我们探讨了用微量镁合金 化改善Fe_3Al和FeAl室温拉伸塑性的可能性。 二、试验方法 试验合金用工业纯铁、纯铝和铝镁中间合金作为原 材料,在10kg真空感应炉中熔炼并真空精铸成标准拉伸 I. Preface Due to the long-range orderly intermetallic compounds Fe3Al and FeAl have good properties of high temperature oxidation resistance, low density and low cost, they are valued by material scientists all over the world. However, its room temperature brittleness is a major obstacle to the application of engineering materials. People tried to improve the ductility of both compounds by alloying. Previous studies have shown that a small amount of Cr can significantly improve the room temperature ductility of deformed Fe_3Al alloys. However, our experiments show that adding 2.5at% Cr to Fe_3Al does not significantly improve the ductility at room temperature. Trace boron can make FeAl tensile fracture from transgranular into transcrystallization, plasticity increases, while the absolute value of elongation is still not high. Some people use rapid solidification method to improve plasticity, but the process is complex, the cost is too high, difficult to practical. A simple and feasible way to improve the ductility of polycrystalline Fe 3 Al and FeAl is still alloying. Therefore, it is necessary to further study the use of alloying to improve plasticity. Inspired by superalloy alloying, we discuss the possibility of improving the ductility of Fe 3 Al and FeAl at room temperature with micro-alloying. Second, the test method Test alloy with industrial pure iron, pure aluminum and aluminum-magnesium master alloy as raw materials, vacuum induction furnace 10kg smelting and vacuum casting into a standard stretch