Fatigue and Fracture of Intermetallic Alloys
Abstract
The compound, A13Ti, was alloyed with 7.5 at.% Fe to produce a cubic L12 structure. Ibis material was arc cast and either directly homogenization heat treated (HHT) or comminuted into powder and consolidated by hot isostatic pressing (HIP). Microstructures were carefully evaluated by optical and electron microscopy. Mechanical properties were measured as a function of temperature using compression and flexure. Utilizing a novel test fixture, both monotonic and cyclic tensile properties were determined as a function of temperature for specimens which had been sequentially cast, HIPed, and HHTed. Despite quasi-brittle behavior below 1000 deg C, failure was within the gauge section in most cases. The fracture surfaces showed increasing evidence of ductile tearing as the temperature was increased, and pores were determined to play an important role in the fracture process. The yield strength vs. temperature response was relatively flat up to intermediate temperature, possibly attributable to competing slip systems. The compressive yield strength and strain to failure were typically greater than those measured in tension, particularly at the lower temperatures. The fatigue data were reasonably well behaved, with fatigue specimens showing clear evidence of striations. Attempts to alloy the binary D022 compound with Nb did not produce the desired cubic structure.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 25, 1992
- Accession Number
- ADA254543
Entities
People
- A. F. Giamei
- C. V. Cooper
- H. R. Inoue
- L. H. Favrow
Organizations
- United Technologies Corporation