Rev.Adv.Mater.Sci. (RAMS)
No 1/2, Vol. 45, 2016, pages 20-27

MICROSTRUCTURE TRANSFORMATION IN A CAST Cu-Fe
ALLOY AT HIGH PRESSURE TORSION DEFORMATION

A. Lukyanov, A. Churakova, D. Gunderov, A. Filatov, E. Antipov, V. Sitdikov, A. Ganeev, R. Valiev and V. Pushin

Abstract

The effect of high pressure torsion (HPT) on the microstructure of Cu-Fe 36 wt.% alloy has been studied. The initial Cu-Fe alloy has a dendritic structure, the length of dendrites is up to 100 µm. As a result of HPT (20 anvil revolutions at 400 °C) a nanostructural state is formed. The average size of the Cu and α-Fe grains is 60 and 35 nm correspondingly. The volume fraction of the Fe phase reduces from the initial 37% down to 15% after HPT. The concentration of iron dissolved in the copper lattice reaches 20%. The subsequent annealing at 700 °C for 1 hour results in some coarsening of α-Fe particles, as compared to the state after HPT. However, the typical dendritic structure of the cast alloy does not recover; it remains dispersed with the size of α-Fe particles less than 20 µm. As a result of HPT the alloy microhardness increased from 1800 to 4000 MPa. The subsequent annealing at T = 700 °C decreased the microhardness to 2700 MPa, but this value is 1.5 times higher than that in the initial as cast state.

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