Accession Number:

ADA237064

Title:

Lightweight Disk Alloy Development

Descriptive Note:

Final rept. Sep 1986-Apr 1990

Corporate Author:

PRATT AND WHITNEY WEST PALM BEACH FL

Report Date:

1991-04-01

Pagination or Media Count:

223.0

Abstract:

A 3-year program was conducted with the intention of developing NiAl- base alloys with mechanical and physical properties suitable for use as a lightweight turbine disk material. The program emphasized overcoming the room temperature brittleness problem and enhancing high temperature strength and creep resistance. Two approaches were utilized to address the room temperature brittleness problem alloying to change the ordering energy to modify the slip behavior and exploiting a variety of martensitic transformation mechanisms. Ternary additions of chromium, cobalt, iron, and vanadium were studied at a variety of NiAl compositions. Both Cr and Co additions modify the room temperature slip behavior of NiAl toward one more favorable with respect to Von Mises criterion. However, a change in slip system alone is apparently insufficient for room temperature ductility. Therefore, this approach requires further study. The martensitic transformation mechanisms in Co-modified NiAl alloys were also studies as a means of overcoming the room temperature brittleness problem. The mechanisms of stress-induced martensite, nucleation of additional martensitic variants under stress, and rearrangement of twin lamellae within existing martensitic variants were beneficial and enhance the room temperature ductility and toughness. In addition to the alloy development studies, this program contained fundamental studies of the atomic bond characteristics of B2 compounds as well as computer simulation of flow and fracture of stoichiometric NiAl.

Subject Categories:

  • Properties of Metals and Alloys
  • Jet and Gas Turbine Engines

Distribution Statement:

APPROVED FOR PUBLIC RELEASE