Effect of Mn Addition on Microstructural Changes and Mechanical Properties of Ti-5Al-2.5Fe Alloys

초록

The microstructures and mechanical properties were investigated in newly developed Ti-5Al-2.5Fe and Ti-5Al-2.5Fe-2Mn alloys, which were fabricated by two-step hot rolling processes. Lamellar structures were observed in the Ti-5Al-2.5Fe-2Mn alloy aged at 600 degrees C for 24 h, depending on the viewing directions (normal, rolling, and transverse). In the aged Ti-5Al-2.5Fe alloy, a spheroidized alpha matrix and TiFe precipitates in the alpha grain boundary were observed, with a crystallographic orientation relationship of (011)(TiFe)//(011 over bar 0)(alpha). It was found that Mn addition improved the mechanical properties, attributed to the increased beta phase (approximately 4.3 times relative to the Ti-5Al-2.5Fe alloy) and solid solution strengthening. Interestingly, in the Ti-5Al-2.5Fe alloys, the oxygen was enriched by the TiFe phase rather than the alpha phase, which may weaken the oxygen solute dragging effect.

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