Accession Number : ADA319912

Title :   Fatigue Mechanisms in Metallic Matrix Composites.

Descriptive Note : Final rept. 1 Jul 95-30 Jun 96,

Corporate Author : CALIFORNIA UNIV IRVINE

Personal Author(s) : Earthman, James C. ; Lavernia, Enrique J.

PDF Url : ADA319912

Report Date : AUG 1996

Pagination or Media Count : 13

Abstract : Fatigue crack growth in alumina particulate reinforced Ni3Al alloy composites, IC-50/Al2O3, fabricated using a spray deposition and co-injection process was examined and compared with that in a conventional nickel-based superalloy, Inconel 718. Single edge-notched fatigue crack growth specimens were tested under constant dK conditions using a custom fully automated servo-hydraulic test system. The results indicate that the threshold value of dK is at least as high as that for monolithic IC-5O, regardless of whether the composite is in the as-sprayed or HIPed condition. However, the HIPed microstructure exhibits a higher fatigue crack growth resistance in the Paris law regime compared to the as-sprayed material. Both composites exhibit a lower crack growth resistance compared to that for unreinforced IC-5O. Compared with Inconel 718, the present IC-5O MMCs consistently exhibit substantially better fatigue crack growth resistance properties.

Descriptors :   *METAL MATRIX COMPOSITES, *CRACK PROPAGATION, *SUPERALLOYS, MICROSTRUCTURE, FATIGUE LIFE, FIBER REINFORCED COMPOSITES, NICKEL ALLOYS, FATIGUE TESTS(MECHANICS), CYCLIC LOADS, ALUMINIDES, MICROCRACKING.

Subject Categories : Laminates and Composite Materials
      Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE