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Vacuum effects on fatigue crack growth in submicrometre‐thick freestanding copper films
Author(s) -
Kondo Toshiyuki,
Shin Akihiro,
Akasaka Masaya,
Hirakata Hiroyuki,
Minoshima Kohji
Publication year - 2019
Publication title -
fatigue and fracture of engineering materials and structures
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.887
H-Index - 84
eISSN - 1460-2695
pISSN - 8756-758X
DOI - 10.1111/ffe.12976
Subject(s) - paris' law , materials science , nucleation , copper , composite material , crack closure , metallurgy , fracture mechanics , chemistry , organic chemistry
Abstract To clarify vacuum effects on fatigue crack growth in freestanding metallic thin films, experiments were conducted on approximately 500‐nm‐thick copper films inside a field emission scanning electron microscope. Fatigue crack growth accompanied by intrusion/extrusion formation occurred in vacuum, and d a /d N was smaller than in air in the middle‐Δ K region (Δ K ≈ 1.7‐3.1 MPam 1/2 ). Conversely, in the low‐Δ K region (Δ K ≲ 1.7 MPam 1/2 ), d a /d N was larger in vacuum than in air. Further, fatigue crack growth in vacuum occurred below the fatigue threshold in air (Δ K th,air ). A nonpropagating crack after reaching Δ K th,air continued to propagate in vacuum when the environment changed from air to vacuum. This indicates that fatigue crack growth resistance is smaller in vacuum than in air under the same effective driving force. The fatigue damage area near the crack paths in vacuum in the low‐Δ K region became wider, suggesting that the nucleation of fatigue damage was enhanced in vacuum.