Low cycle fatigue behaviour of a precipitation hardened Cu-Ni-Si alloy

Abstract

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

Unusual dynamic precipitation softening induced by dislocation glide in biomedical beta-titanium alloys

“…As described in the introduction, there have been many reports on the cyclic softening of metallic materials that contain precipitates, including Ti alloys 30 – 34 . In these materials, the softening is known to occur through dissolution of the precipitates because the to-and-fro motion of the dislocation cuts the precipitates and assists in their dissolution, as schematically indicated in Fig.…”

Tuning Low Cycle Fatigue Properties of Cu-Be-Co-Ni Alloy by Precipitation Design

“…The LCF behaviors of the precipitation strengthening alloy are closely related to the states of precipitation. Delbove et al [6] investigated the role of the microstructure on the LCF behavior of Cu-Ni-Si alloy and reported that dislocation sheared the δ-Ni 2 Si precipitates, causing the dissolution of precipitates and local plastic deformation. According to the research of Hockauf et al [7] on aluminum alloys, the precipitates which were coherent with the parent phase contributed to slip localization, resulting in early failure during LCF loading.…”

Characterization of uniaxial fatigue behavior of precipitate strengthened Cu-Ni-Si alloy (SICLANIC(TM))

“…However, the cyclic circulation of alternating current induces fatigue failure during the high frequency electromagnetic applications [5]. Fatigue behavior of Cu-Ni-Si alloys has been investigated in few articles [6][7][8][9]. In [6], authors investigated the microstructure of the material at different heat treatment states and its influence on the low cycle fatigue (LCF) and high cycle fatigue (HCF).…”

“…Fatigue behavior of Cu-Ni-Si alloys has been investigated in few articles [6][7][8][9]. In [6], authors investigated the microstructure of the material at different heat treatment states and its influence on the low cycle fatigue (LCF) and high cycle fatigue (HCF). They have noticed a softening effect of the copper alloy under LCF [6].…”

“…In [6], authors investigated the microstructure of the material at different heat treatment states and its influence on the low cycle fatigue (LCF) and high cycle fatigue (HCF). They have noticed a softening effect of the copper alloy under LCF [6]. Goto et al [8] studied the role of the Ni2Si curing compound in fatigue crack initiation and propagation mechanism and identified a localized fatigue behavior.…”