Low cycle fatigue tests were performed at room temperature to investigate the role of the microstructure of a Cu-Ni-Si alloy on the stress response to strain cycling and on the fatigue resistance. The cyclic accommodation consisted in a hardening followed by a softening. TEM analysis showed that in some grains dislocations remained isolated and confined between precipitates while in other grains dislocations piled up at δ-Ni 2 Si precipitates and then cut them. Repetitive cutting allows their dissolution and formation of precipitate-free bands where the plastic deformation is localised. The Manson-Coffin diagram exhibited two regimes according to the proportion of grains involved in the plastic deformation accommodation. Keywords copper alloys-cyclic properties-low cycle fatiguemicrostructure-microscopy Highlights Investigated Cu-Ni-Si contains δ-Ni 2 Si nano precipitates-Cyclic hardening followed by softening is observed-Dissolution of δ-Ni 2 Si results from repetitive cutting-Deformation is localised in precipitate-free bands Highlights Investigated Cu-Ni-Si contains a high density of δ-Ni Si precipitates-Cyclic hardening followed by softening is observed-Dissolution of δ-Ni 2 Si results from repetitive cuttinglocalisation of deformation in precipitate-free bands

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