Accession Number:

ADA254543

Title:

Fatigue and Fracture of Intermetallic Alloys

Descriptive Note:

Final rept. 1 Apr 1989-31 Mar 1992

Corporate Author:

UNITED TECHNOLOGIES RESEARCH CENTER EAST HARTFORD CT

Report Date:

1992-07-25

Pagination or Media Count:

72.0

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.

Subject Categories:

  • Metallurgy and Metallography
  • Properties of Metals and Alloys
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE