SiCウィスカ強化アルミニウム基複合材料の微小疲労き裂発生と進展

概要

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Reversed plane bending fatigue tests were conducted on SiC whisker reinforced aluminum composite specimens with shallow surface notch. Initation and growth behavior of small surface fatigue cracks were investigated by means of a plastic replica technique. Fatigue strength of composite was higher than that of unreinforced alloy because SiC whiskers restricted cyclic slip deformation of matrix. which resulted in the delay of fatigue crack initiation. the initiation of small fatigue crack in composite was found characterized by the interface cracking between matrix and SiC whiskers, where the lump of SiC whiskers was composed in a manufacturing process. The many small cracks initiated as the lumps of SiC whiskers distributed around specimen surface irrespective of the stress revel, while several cracks grew simultaneously in the tests with high stress amplitude and one main crack propagated in those with low stress one. Microscopically, the coalescence of main crack and micro cracks was observed frequently. The difference of small fatigue crack growth rate between composite and unreinforced alloy was small, which implied SiC whisker was not resistant to crack growth but to crack initiation. The crack growth rate of small cracks was found faster than that of long cracks.
一般社団法人日本機械学会の論文
1998-01-25