Microstructural change with Co content together with heat treatment was studied in rapidly solidified Al-Cu-Fe-Co alloys using X-ray diffractometry and transmission electron microscopy. With an increase in Co content in the as-cast Al65Cu20Fe15-xCox alloys, the relative amount of the icosahedral phase drastically decreased and that of the decagonal phase increased. In the as-melt spun alloys, effects of Co content are critically changed at around 5 at% Co. For the less Co containing alloys (below 5 at%), the icosahedral phase proved to be the major phase, while the 5 at% Co containing alloy showed the coexistence of the icosahedral and decagonal phases. The 8 at% containing alloy showed the monolithic decagonal phase in the as-melt spun state. Unlike as-cast alloys, all the as-melt spun alloys showed no trace of the λ-phase. However, after heat treatment of ribbons, λ-phase newly appeared in the Al65Cu20Fe10Co3 and Al65Cu20Fe10Co5 alloys. The λ-phase showed orientation relationships with surrounding icosahedral or decagonal phases.
Bibliographical noteFunding Information:
This work was supported by the Creative Research Initiatives of the Korean Ministry of Science and Technology. One of the authors (S.H.K.) thanks the Korean Science and Engineering Foundation for financial support.
All Science Journal Classification (ASJC) codes
- Mechanics of Materials
- Mechanical Engineering
- Metals and Alloys
- Materials Chemistry