Nanocomposites and nanomaterials

Formation of metastable intermetallics in Al-Cu system during mechanical alloying
 Matvienko Ya.I., Polishchuk S.S., Lakhnik A.M., Rud A.D.

G. V. Kurdyumov Institute for Metal Physics of the NAS of Ukraine
36, academician Vernadsky blvd, UA-03142 Kiev, Ukraine 
E-mail: yana_matv@ukr.net
	
Due to the low weight and excellent mechanical properties aluminum-based alloys and Al matrix composites have been widely used in automobile and aerospace industries. Mechanical alloying (MA) is believed to be an advanced tool for processing novel materials and optimizing their physical properties through microstructure modification. Complex mechanisms of intermixing and solid-state reactions induced by high-energy ball milling allow fabrication of dispersion strengthened materials, supersaturated solid solutions, complex intermetallics and nanocrystalline materials [1].
As the binary Al-Cu system exhibits not large negative heats of phase formation it was expected that the reaction between Al and Cu can easily take place. The purpose of the present work was to study the phase formation in the Al-rich region of Al-Cu system during high-energy ball milling depending on various process parameters 
 The synthesis of Al-Cu intermetallics from elemental Al and Cu powders with a total composition in the range from Al-17wt%Cu to Al-50wt.%Cu has been performed during ball milling in argon atmosphere for different milling time and rotation speeds. Identification and quantification of the phases have been carried out using X-ray diffraction. 
 It was found that MA process leads to the Al2Cu phase formation after only 1 hour of milling in Al-33wt % Cu eutectic alloy. The formation of other AlCu and Al9Cu4 metastable phases are discussed. Stable nanostructured phases of Al and Al2Cu were found after milling for more than 6 hours. 
The research has been carried out under financial support of the budget themes of the G.V. Kurdyumov Institute for Metal Physics of the National Academy of Sciences of Ukraine #55-16.    

1.	Besson R..M,  Avettand-Fenoel M.-N., Thuinet L., Know J., Addad A., Roussel  P., Legris A.  Mechanisms of formation of Al4Cu9 during mechanical alloing: An experimental study // Acta Materialia.-2015.-87-P. 216-224.