Microstructure-mechanical property relationship to copper alloys with shape memory during thermomechanical treatments

摘要

The phase transformations during fabrication and aging after cold deformation in three polychrystalline copper alloys of the Cu-Al-Ni system with shape memory effect (SME) were characterized. Some phase transformations were identified with clear repercussion in their mechanical properties during thermomechanical treatments. Around 430 °C, mutual effects of β-phase recrystallization and precipitation of γ2 and NiAl phases were observed. Close to 600 °C the dissolution of phase α was observed, beginning transformation into β phase process. Brittle phases such as γ2 and NiAl began to precipitate during a short exposure time at 380 °C, 585 °C, 600 °C, and 700 °C temperatures. The phase transformations were intensified due to the plastic deformation that acted as a driving force for the diffusion processes. The introduction of chemical elements inhibited the grain growth and increased the structural disorder generating an elevation in the hardness property.