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 thermo-mechanical treatments. Around 430 deg C, mutual effects of beta-phase recrystallization and precipitation of gamma_2 and MAI phases were observed. Close to 600 deg C the dissolution of phase a was observed, beginning transformation into beta phase process. Brittle phases such as gamma _2 and NiAl began to precipitate during a short exposure time at 380 deg C, 585 deg C, 600 deg C, and 700 deg 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.