Powder Metallurgy Processing of Dual Phase Al Rich Fe-Al Intermetallics

摘要

A powder metallurgy technique was used to fabricate two different dual-phase Al-rich Fe-Al intermetallics, namely, FeAl2-Fe2Al5 and FeAl3-Fe2Al5. Powders were first produced by inert gas atomization, and then subsequently consolidated by hot pressing at 1120 deg C with the addition of 2 v/o pure Al. X-ray diffraction studies confirmed the formation of dual-phase compounds FeAl2-Fe2Al5 and FeAl3-Fe2Al5 with no residual Al. The density of the hot pressed materials was measured to be approximately 96% of theoretical. The grain/phase size was determined to be 44 micrometers and 23 micrometers for consolidated FeAl2-F2eAl5 and FeAl3 -Fe2Al5 respectively. Oxidation resistance of the two alloys was also studied and compared to other intermetallics. It was found that hot pressed materials exhibited inferior oxidation resistance, while cast materials showed a comparable oxidation resistance to that of other aluminides. The room temperature fracture toughness, determined on the basis of hardness indentation, was found to be slightly over 1.0MPa m(1/2) for both alloys. The low fracture toughness in these alloys was attributed to their complex crystal structures. jg p2.