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Crack deflection during fatigue and monotonic fracture of a SiC whisker reinforced 2009 aluminium alloy

Journal Article · · Acta Metallurgica et Materialia; (United States)
 [1]; ;  [2]
  1. Tsinghua Univ., Beijing (China). Dept. of Mechanical Engineering
  2. Univ. of Cambridge (United Kingdom). Dept. of Materials Science and Metallurgy

Fatigue crack growth under Mode 1 loading, and static fracture in both symmetrical and asymmetrical notched four point bends specimens, have been examined in SiC whisker reinforced 2009 aluminium alloy. In the fatigue tests a range of orientations of the starter notch, with respect to the extrusion direction, L, was examined. Slanted crack propagation was observed in all specimens except that in the T-L configuration. For the monotonic tests the specimen orientation (L-T) remained constant whilst the ratio of Mode 1 to Mode 2 loading was varied. Again crack deflection was observed in all cases apart from the L-T specimen under pure Mode 1 loading. Whisker debonding was found to be the dominant factor controlling crack deflection, Independent of the mixing of the loading mode. Under mixed-mode static loading, the deflection angle was controlled by the average orientation of the whiskers subject to the asymmetrically distributed maximum principal stress. In fatigue loading, however, the crack tended to follow the most frequently observed whisker orientation. These contrasting observations are interpreted in terms of the different sampling volumes at the crack tip in monotonic fracture and in fatigue crack growth.

OSTI ID:
7276545
Journal Information:
Acta Metallurgica et Materialia; (United States), Journal Name: Acta Metallurgica et Materialia; (United States) Vol. 42:7; ISSN 0956-7151; ISSN AMATEB
Country of Publication:
United States
Language:
English