Microstructural Investigation and Phase Relationships of Fe-Al-Hf Alloys


Yıldırım M., Akdeniz M. V. , Mekhrabov A.

METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, ss.3412-3421, 2014 (SCI İndekslerine Giren Dergi) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Basım Tarihi: 2014
  • Doi Numarası: 10.1007/s11661-014-2287-0
  • Dergi Adı: METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
  • Sayfa Sayıları: ss.3412-3421

Özet

The effect of Hf addition on microstructures, phase relationships, microhardness, and magnetic properties of Fe50Al50-n Hf (n) alloys for n = 1, 3, 5, 7, and 9 at. pct has been investigated. At all investigated compositions, the ternary intermetallic HfFe6Al6 tau (1) phase forms due to the limited solid solubility of Hf in FeAl phase and tends to develop a eutectic phase mixture with the Fe-Al-based phase. The Hf concentration of the eutectic composition is found to be 7 at. pct from the microstructural examinations and the eutectic phase transition temperature is determined as 1521 K (1248 A degrees C) independent of Hf amount by differential scanning calorimetry measurements. Furthermore, the enthalpies and activation energies (based on Kissinger and Ozawa methods) of eutectic phase transitions are reported. The minimum activation energy is calculated for the fully eutectic composition. Moreover, variation of the microhardness of Fe-Al-based alloys as a function of the Hf content is investigated, and its dependence on the thermal history of the alloys is explained. (C) The Minerals, Metals & Materials Society and ASM International 2014