Fabrication of Bulk (Fe,Cr)_3Al/Al_2O_3 Intermetallic Matrix Nanocomposite Through Mechanical Alloying and Sintering

摘要

In the present study,(Fe,Cr)_3Al/20 vol% Al_2O_3 nanocomposite was prepared through mechanochemical reactions during ball milling and successfully bulked using a combination of cold isostatic press and sintering at 1400 ℃ for 1 h. Two processing approaches were utilized to produce(Fe,Cr)_3Al/Al_2O_3 nanocomposite: The first was milling of Fe, Cr,Al and Fe_2O_3, while the second one was milling of Fe, Cr, Al and Cr_2O_3, both in stoichiometric condition, to synthesize(Fe,Cr)_3Al/20 vol% Al_2O_3. Structural changes of powder particles during mechanical alloying were studied by X-ray diffraction. The microstructure and the morphology of powder particles and bulk samples were also studied by scanning electron microscopy and transmission electron microscopy. Microstructural analysis showed that mechanochemical reactions took place during milling, and nanometric Al_2O_3 was uniformly distributed in the matrix. The results also showed that the second approach required a considerably higher milling time to produce(Fe,Cr)_3Al/Al_2O_3 nanocomposite, as compared to the first one. For this reason, bulk samples were produced from the synthesized nanocomposite in the first approach. The microstructure of the sintered samples consisted of a network structure of(Fe,Cr)_3Al and Al_2O_3 phases with superior mechanical properties.