Structures of Al-based nanocomposites of Al-Fe alloys prepared by mechanical alloying (MA) and subsequent annealing are compared with those obtained by rapid solidification processing (RSP). MA produced only supersaturated solid solution of Fe in Al up to 10 at.% Fe, while for higher Fe content up to 20 at.% the nonequilibrium intermetallic Al5Fe 2 appeared. Subsequent annealing at 673 K resulted in more Al 5Fe2 formation with very little coarsening. The equilibrium intermetallics, Al3Fe (Al13Fe4), was not observed even at this temperature. In contrast, ribbons of similar composition produced by RSP formed fine cellular or dendritic structure with nanosized dispersoids of possibly a nano-quasicrystalline phase and amorphous phase along with α-Al depending on the Fe content in the alloys. This difference in the product structure can be attributed to the difference in alloying mechanisms in MA and RSP. © Indian Academy of Sciences.

Budaraju Srinivasa Murty

Department of Metallurgical and Materials Engineering

Alloying

Alloys

Aluminum

Annealing

Crystallization

Iron alloys

Mechanical Alloying

Metallic compounds

Metallurgy

Nanocomposites

Nanostructured materials

Solid solutions

Solidification

AL-FE

AL-FE ALLOYS

FE CONTENT

Intermetallic

Non-equilibrium

QUASICRYSTALLINE

RAPID SOLIDIFICATION PROCESSING

Subsequent annealing

SUPERSATURATED SOLID SOLUTION

Rapid Solidification

Fulltext

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IIT Madras

Bulletin of Materials Science

Aluminium alloys reinforced with transition metal aluminide (Al 3Ti, Al3Fe, Al3Ni, etc.) particles possess high specific strength both at ambient and elevated temperature. The improved strength of these alloys are the results of slower coarsening rate of the intermetallic particles due to low diffusivity of the transition metals in aluminium. However, the strength can be enhanced further by refining the microstructure of the alloys to nanometer range. The authors have successfully attempted two important non-equilibrium processing techniques i.e. rapid solidification processing (RSP) and mechanical alloying for the refinement of the microstructure in various aluminium alloys. In this report, authors present a short review of their work on RSP of Al-Ti and Al-Fe alloys to produce nanocomposites.

Transactions of the Indian Institute of Metals

Nanocomposites of aluminum alloys by rapid solidification processing

In the present work the structure and morphology of the phases of nanocomposites formed in rapidly solidified Al-Fe alloys were investigated in details using analytical transmission electron microscopy and X-ray diffraction. Nanoquasicrystalline phases, amorphous phase and intermetallics like Al5Fe2, Al13F4 coexisted with α-Al in nanocomposites of the melt spun alloys. It was seen that the Fe supersaturation in α-Al diminished with the increase in Fe content and wheel speed indicating the dominant role of the thermodynamic driving force in the precipitation of Fe-rich phases. Nanoquasicrystalline phases were observed for the first time in the dilute Al alloys like Al-2.5Fe and Al-5Fe as confirmed by high resolution TEM. High hardness (3.57GPa) was measured in nanocomposite of Al-10Fe alloy, which was attributed to synergistic effect of solid solution strengthening due to high solute content (9.17at.% Fe), dispersion strengthening by high volume fraction of nanoquasicrystalline phase; and Hall-Petch strengthening from finer cell size (20-30nm) of α-Al matrix. © 2011 Elsevier B.V.

Materials Science and Engineering A

Formation of metastable phases and nanocomposite structures in rapidly solidified Al-Fe alloys

Alloy Phase Diagrams

Fe (Iron) Binary Alloy Phase Diagrams

Progress in Materials Science

Electronic structure of complex Hume-Rothery phases and quasicrystals in transition metal aluminides

MATERIALS TRANSACTIONS

Composed Phases and Microhardness of Aluminium-Rich Aluminium-Iron Alloys Obtained by Rapid Quenching, Mechanical Alloying and High Pressure Torsion Deformation

Materials Science and Engineering: A

Synthesis of nanocrystalline materials — an overview

Structure of nanocomposites of Al-Fe alloys prepared by mechanical alloying and rapid solidification processing

Journal	Bulletin of Materials Science
ISSN	02504707
Open Access	Yes