In situ TEM technique was employed to investigate the influence of the lamellar structure on crack propagation in two-phase alloys. It was found that the way of crack propagation in lamellar structure depends strongly on the angle between crack growth and lamellar lath direction. Only if crack growth is roughly parallel to lamellar interface, microcracks nucleate at interfaces ahead of the main crack and the crack propagates by ligament break. Therefore, shear ligament toughening plays an important role under this condition. When crack growth is perpendicular to lamellae or between perpendicular and parallel, the crack propagation is inhibited by lamellar interfaces and the crack tips are blunted by lamellar interface separating or sliding. The crack propagates by tearing lamellae and accompanies a larger strain area around the crack tips. However, microcracks rarely occur under this condition. Microcracks are always nucleated in α2 lamellae. Two kinds of mechanisms of microcrack nucleation vary with the angle between crack growth and lamellar lath direction. As crack growth is parallel to the lamellae, the stress field ahead of crack tip may play a dominant role. As crack growth is perpendicular to lamellae, local stress concentration caused by interaction between deformation process and α2/γ interface and external stress induce α2 lamellae fracture and microcrack formation.
|出版ステータス||Published - 1995 12月 1|
|イベント||Proceedings of the 1995 124th TMS Annual Meeting - Las Vegas, NV, USA|
継続期間: 1995 2月 13 → 1995 2月 16
|Other||Proceedings of the 1995 124th TMS Annual Meeting|
|City||Las Vegas, NV, USA|
|Period||95/2/13 → 95/2/16|
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