Effect of 160.DEG.C. Annealing on the Fatigue Damage and Small Crack Growth Behavior of Ultrafine Grained Copper

Goto, Masahiro; Teshima, Norihiro; Han, Seong Ho; Yakushiji, Terutoshi; Himeno, Takamasa; Kawagoishi, Norio

doi:10.1299/kikaia.74.1006

Cited by 3 publications

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“…8(b). It is reported that the intergranular fatigue crack can be observed even at the room temperature in the ultrafine grained copper with a grain size of 300nm (8) . Although the grain size of the copper used in the experiment is much larger than that of the ultrafine grained one, the intergranular fatigue crack is often observed in the copper film with thickness of t f =100mm.…”

Section: Crystal Orientation Map and Fracture Surfacementioning

confidence: 99%

OS12F123 Evaluation of Fatigue Crack Propagation Behavior in Copper Films Based on Measurement of Crack Opening Displacement Distribution

Shimizu

Natsumeda

Chikaishi

2011

ATEM

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It has become important to investigate the fatigue properties of film materials in electronic devices. In this study, in order to investigate the fatigue behavior of copper films, pure copper films of 100mm thickness with mean grain sizes of 30mm and 15mm were fatigued under constant stress amplitudes of 30, 35 and 40MPa with a stress ratio of R=0. A crack opening displacement distribution was measured by using a digital image correlation method. Additionally, a crystal orientation around the fatigue crack was analyzed by using an EBSD (Electron Back-scatter Diffraction) method. As a result, zigzag patterns of the fatigue crack in the film with a large grain size were larger than those in the film with a small grain size and the fatigue crack initiation and the propagation from the notch hole in the film were faster for the film with a large grain size than for the film with a small grain size under the same stress amplitude. A relationship between a stress intensity factor range, DK est , estimated from the crack opening displacement distribution by using an extrapolation method and a fatigue crack propagation rate, da/dN, can be correlated regardless of the grain size and the stress amplitude except near the fatigue crack propagation threshold. The intergranular fatigue crack path is often observed on the film surface from the EBSD measurement, especially in the film with a small grain size. On the other hand, transgranular fracture surfaces with a plastic deformation can be seen inside of the film from the observation of fracture surfaces by using a scanning electron microscope. The large grain in front of the fatigue crack is expected to restrain the fatigue crack propagation while the intergranular crack can propagate in the film with small grains even below the fatigue crack propagation threshold for the film with large grains.

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Section: Crystal Orientation Map and Fracture Surfacementioning

confidence: 99%