Accession Number:

ADA270305

Title:

Fatigue Resistant Ti3A1 Composites

Descriptive Note:

Final rept. 28 Sep 1990-27 Sep 1992

Corporate Author:

ROCKWELL INTERNATIONAL CORP THOUSAND OAKS CA SCIENCE CENTER

Report Date:

1993-01-01

Pagination or Media Count:

72.0

Abstract:

Measurements of interfacial properties and residual stresses in Tl3 AlSiC composites with and without ductile AgTa layers are presented as the first step in determining the role of the ductile layers in the fatigue of these composites. In the composite without ductile layers, debonding and fiber sliding occurred along the interface between the outer surface of the fiber and the layer of reaction products. In the composite with AgTa layers, debonding and sliding occurred within the SCS-6 layers that form the outer part of the fiber, with a higher frictional stress resisting sliding 100 MPa c.f. 66 MPa. Fatigue crack growth measurements indicated only minor differences in growth rates in the two composites in a given environment, but both composites exhibited much larger growth rates in air than in vacuum. High resolution crack opening displacement measurements are used to assess relative bridging effects. To avoid the limitation imposed by the presence of weak SCS-6 layers on the SIC fibers, a composite composed of sapphire fibers In matrix of Ti3Al with an interfacial layer of Ta was fabricated. In situ observations during transverse loading Indicated that the interfacial bonding was sufficiently strong that interfacial debonding or plasticity did not affect transverse properties.... Titanium aluminide composites, Interface properties, Transverse failure.

Subject Categories:

  • Inorganic Chemistry
  • Laminates and Composite Materials
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE