Development of directionally solidified eutectic nickel alloys for use in aircraft gas turbines at metal temperatures exceeding 1000 C. Final report Jan--Oct 76. [Nickel-base alloy with varying substitutions]
Investigations to develop an isotropically ductile high temperature eutectic by ternary modifications and quaternary or quinary additions to the monovariant eutectic gamma/gamma-alpha (Ni/sub 3/Al/Ni--Mo) were performed. Extensive substitutions (>7 w/o) of chromium, cobalt, iron and tantalum and more limited substitution of tungsten, rhenium, titanium, and carbon demonstrated the wide flexibility of alloying. Tantalum and rhenium additions improved the high temperature creep strength and tantalum additions combined with chromium (i.e. Ni--32 w/o Mo--5.5 w/o Al--3 w/o Cr--1 w/o Ta) yielded an alloy whose cyclic oxidation resistance at 1000 C compared favorably to the outstanding oxidataion resistant nickel-base superalloy, B-1900. Since the measured coefficient of thermal expansion (CTE) of gamma/gamma-alpha alloys are below the CTE's of conventional coatings, the requirement of a compatible lower expansion coating was indicated. The ultimate shear strengths of gamma/gamma-alpha alloys at intermediate temperatures (760--880 C) were found to be equivalent to nickel base superalloys. However, the shear creep rupture properties at 760 C were below those of the more isotropic superalloys. The thermal fatigue resistance of gamma/gamma-alpha alloys was found to be dependent on aluminum content. Alloys containing 7.8 w/o Al exhibited substantially greater resistance to cyclic thermal fatigue (400--1122 C) under stress than both D.S. Mar M200 + Hf and gamma/gamma-delta.
- Research Organization:
- United Technologies Research Center, East Hartford, CT (USA)
- DOE Contract Number:
- N62269-76-C-0107
- OSTI ID:
- 7304010
- Report Number(s):
- AD-A-037246; UTRC/R-76-912518-3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AIRCRAFT
GAS TURBINES
ALUMINIUM ALLOYS
MECHANICAL PROPERTIES
CHROMIUM ALLOYS
COBALT ALLOYS
TURBINE BLADES
IRON ALLOYS
MOLYBDENUM ALLOYS
NICKEL BASE ALLOYS
TANTALUM ALLOYS
CREEP
EUTECTICS
FATIGUE
HEAT RESISTING ALLOYS
SHEAR PROPERTIES
VERY HIGH TEMPERATURE
ALLOYS
HEAT RESISTANT MATERIALS
MATERIALS
NICKEL ALLOYS
TURBINES
TURBOMACHINERY
360103* - Metals & Alloys- Mechanical Properties