MA-PAS和MA-HP烧结制备的Fe_3Al金属间化合物的组织和力学性能

以机械合金化Fe-28%Al（摩尔分数）合金粉末为原料,分别采用等离子活化烧结（PAS）和热压烧结（HP）方法制备致密度高达99%的Fe3Al金属间化合物。XRD和TEM测试结果表明：PAS烧结试样保留了机械合金化粉末的A2无序结构,并呈现出亚微米晶粒区域（〉1μm）和纳米晶粒区域（〈500nm）双峰分布的特征,而HP烧结试样为部分D03有序结构,晶粒尺寸在1～2μm的范围内。压缩试验表明：在室温至800℃的条件下,采用两种方法烧结的Fe3Al金属间化合物具有近似的压缩强度,虽然当温度超过400℃后压缩屈服强度均急剧下降,但在800℃时其压缩屈服强度仍高达100MPa,远高于铸造态Fe3Al金属间化合物。相比于HP烧结和铸造态Fe3Al金属间化合物,PAS烧结Fe3Al金属间化合物表现出优异的室温塑性,其室温压缩工程应变为20%。组织结构分析和力学性能测试结果表明,超细晶无序组织有利于Fe3Al金属间化合物室温塑性和高温强度的同时增强。

Microstructure and mechanical properties of Fe_3Al alloys prepared by MA-PAS and MA-HP

Fe₃Al alloys with nearly full density were fabricated by plasma activated sintering (PAS) and hot pressing (HP) from mechanical alloyed Fe-28%Al (mole fraction) powders, respectively. It is found that A2-type Fe₃Al alloys were obtained by PAS, and they had a heterogeneous grain size distribution, most areas had a grain size smaller than 500 nm, and other areas had a grain size of about 1 μm. Different to PAS, D0₃-type Fe₃Al alloys with a grain size of of 1-2 μm were obtained by HP. The compression testing results show that yield strength values of Fe₃Al alloys fabricated by PAS and HP are almost equal at an elevated temperature, and the compression yield strength was about 100 MPa for all at 800 °C. The room temperature compression ductility of Fe₃Al alloys by PAS was about 20%, which was superior to that of Fe₃Al alloys prepared by HP and casting.