Grain refinement of intermetallic compounds in the Cu–Sn system under high pressure torsion

• As cast Cu–36 wt% Sn contains the alternating ε and ζ coarse-grained plates.
• After high pressure torsion the ε and ζ phases become ultrafine-grained.
• However, the shape of ε and ζ plates remains unchanged.
• This unusual behavior is due to the high hardness of ε and ζ phases.

The Cu–36 wt% Sn alloy was subjected to the high pressure torsion (HPT) at room temperature. Before deformation the microstructure was composed of alternating coarse-grained plates of the ζ and ε compounds (Hume-Rothery electronic phases). HPT led, as usual, to the strong grain refinement and increase of dislocation density. However, the macroscopic shape of ζ and ε plates remained unchanged. It means that the refinement took place in each phase individually, i.e. inside the respective ζ and ε plates. High angle grain boundaries are more pronounced in ε phase. This unusual behavior of the alloy is connected with a high hardness of the ζ and ε intermetallic compounds.

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