Microstructure and Mechanical Properties of Mechanically Alloyed and HIP-Consolidated Fe3Al

Blended elemental Fe and Al powders were mechanically alloyed in a high energy attritor-type ball milling system. After 100 h milling, a Fe(Al) solid solution with bcc structure was formed in the powders. An ultra-high pressure (1 GPa) hot isostatic pressing (HIP) facility was used in an effort to consolidate the mechanically alloyed powders into fully dense compacts while retaining the nanocrystalline microstructure. Fully dense Fe3Al compacts with a grain size of 180 nm were obtained by HIP treatment at 1073 K, whilst a 973 K HIP treatment produced nearly full density Fe3Al compacts with a grain size of 80 nm. Mechanical properties of the HIPed compacts were evaluated by compression tests from room temperature to 1073 K and compared with those of a coarse-grained cast Fe3Al alloy. The 973 K HIPed compact exhibited a yield strength as high as 2.3 GPa at room temperature, but it suffered from poor ductility. The 1073 K HIPed compact appears promising due to a combination of significantly higher strength, both at room temperature and at elevated temperatures, as well as better room temperature ductility than its cast counterpart.