skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Thermal Aging Effects on the Mechanical Properties of As-Cast Ni 3Al-based Alloy

Abstract

A series of tensile tests were conducted at room and elevated temperatures on specimens of the alloy known as IC221M (Ni-8.2Al-7.6Cr-1.5Mo-2.1Zr, wt%). Specimens were tested in the as-cast condition or after aging in either air or Ar for up to 1000 h at 900-1100 XC. Room temperature yield strength decreased continuously with aging time at 900 XC from the as-cast value of 530 MPa to 320 MPa after 1000 h. A similar trend was found for hardness. The strength reductions with aging time at 900 XC were similar for aging in either air or Ar. For aging at 1050 XC and 1100 XC, aging in air caused significant strength loss that was attributed to aggressive oxidation. The room temperature yield strength of specimens aged in Ar increased for aging at 1050 XC and 1100 XC. Microhardness testing also showed that specimens aged at 1100 XC had higher hardness than those aged at 900 XC. Analysis using equilibrium thermodynamics suggested that the increases of yield strength and hardness resulted from increasing the amount of fine S precipitation in the alloy matrix. For testing at elevated temperatures, the as-cast alloy had room temperature yield strength of 530 MPa that increased continuously upmore » to a value of 650 MPa at 700 XC. Aging in Ar for 1000 h at 900 XC resulted in a room temperature yield strength of 320 MPa that increased to 560 MPa at 700 XC and decrease slightly to 550 MPa at 900 XC. Aging in Ar for 1000 h at 1100 XC produced room temperature yield strength of 435 MPa that increased to 550 MPa at 500 XC and decreased continuously at high test temperatures. The behavior of these specimens was also rationalized using equilibrium thermodynamics to estimate the fractions of coarse and fine S particles in the microstructures.« less

Authors:
 [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1003549
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Science and Engineering A; Journal Volume: 428; Journal Issue: 1-2
Country of Publication:
United States
Language:
English

Citation Formats

Lee, Dongyun, and Santella, Michael L. Thermal Aging Effects on the Mechanical Properties of As-Cast Ni3Al-based Alloy. United States: N. p., 2006. Web. doi:10.1016/j.msea.2006.05.007.
Lee, Dongyun, & Santella, Michael L. Thermal Aging Effects on the Mechanical Properties of As-Cast Ni3Al-based Alloy. United States. doi:10.1016/j.msea.2006.05.007.
Lee, Dongyun, and Santella, Michael L. Sun . "Thermal Aging Effects on the Mechanical Properties of As-Cast Ni3Al-based Alloy". United States. doi:10.1016/j.msea.2006.05.007.
@article{osti_1003549,
title = {Thermal Aging Effects on the Mechanical Properties of As-Cast Ni3Al-based Alloy},
author = {Lee, Dongyun and Santella, Michael L},
abstractNote = {A series of tensile tests were conducted at room and elevated temperatures on specimens of the alloy known as IC221M (Ni-8.2Al-7.6Cr-1.5Mo-2.1Zr, wt%). Specimens were tested in the as-cast condition or after aging in either air or Ar for up to 1000 h at 900-1100 XC. Room temperature yield strength decreased continuously with aging time at 900 XC from the as-cast value of 530 MPa to 320 MPa after 1000 h. A similar trend was found for hardness. The strength reductions with aging time at 900 XC were similar for aging in either air or Ar. For aging at 1050 XC and 1100 XC, aging in air caused significant strength loss that was attributed to aggressive oxidation. The room temperature yield strength of specimens aged in Ar increased for aging at 1050 XC and 1100 XC. Microhardness testing also showed that specimens aged at 1100 XC had higher hardness than those aged at 900 XC. Analysis using equilibrium thermodynamics suggested that the increases of yield strength and hardness resulted from increasing the amount of fine S precipitation in the alloy matrix. For testing at elevated temperatures, the as-cast alloy had room temperature yield strength of 530 MPa that increased continuously up to a value of 650 MPa at 700 XC. Aging in Ar for 1000 h at 900 XC resulted in a room temperature yield strength of 320 MPa that increased to 560 MPa at 700 XC and decrease slightly to 550 MPa at 900 XC. Aging in Ar for 1000 h at 1100 XC produced room temperature yield strength of 435 MPa that increased to 550 MPa at 500 XC and decreased continuously at high test temperatures. The behavior of these specimens was also rationalized using equilibrium thermodynamics to estimate the fractions of coarse and fine S particles in the microstructures.},
doi = {10.1016/j.msea.2006.05.007},
journal = {Materials Science and Engineering A},
number = 1-2,
volume = 428,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • The radiation effccts of 4-Mev deuterons on the electric resistance of ordered Ni/sub 3/Fe and Fe/sub 3/Al alloys and aging of 35% Ni--4.5% Ti--60).5% Fe alloy were invcsiigated. The changes in FeiAl and Ni/sub 3/Fe electric resistance induced by various deuteron beams were tabulated. Irradiation by fluxes up to 5 x 10/sup 16/ deuterons/cm/sup 2/ induced strong changes in the electric conductivity. With a further rise of the iniegral flux, the changes in electric conductivity were not so pronounced. The preliminary thermal treatments of the specimens played an important part in the electric conductivity of the irradiated materials. (R.V.J.)
  • A Ni-Al-Mo directionally solidified (DS) casting [gamma][prime]-base superalloy, with the chemical composition (wt%) 7.5 to 8.5% Ni, 10 to 14% Al, Mo [<=] 0.15% B, has been developed for advanced gas turbine blades and vanes. The mechanical properties of this alloy have been determined by tensile tests at room temperature and in the temperature range 700 to 1,000 C and by stress-rupture tests in the temperature range 760 to 1,100 C. The microstructures of the as-cast and homogenized specimens and of specimen after creep deformation at 1,000 to 1,100 C have been examined by scanning electron microscopy (SEM), transmission electronmore » microscopy (TEM), and optical microscopy techniques. The results show that this alloy has a high yield strength from room temperature up to 1,100 C, excellent creep resistance at temperatures up to 1,100 C, as well as a lower density and higher melting point than currently available nickel superalloys. The microstructural observations and analysis indicate that the superior mechanical properties of this alloy may be attributed to solid solution hardening by the large molybdenum addition, second-phase strengthening by [gamma] phase and other minor phases that precipitate in various temperature ranges, the formation of a [gamma] raft structure during creep, and to the existence of high-density misfit dislocation networks at [gamma][prime]/[gamma] interface areas due to a high value of [gamma][prime]/[gamma] misfit.« less
  • Al{sub 4}B{sub 2}O{sub 9}-whisker-coated Al{sub 2}O{sub 3} ceramics were bonded by AgCu–4.5 wt.%Ti alloy in vacuum. The microstructure of the whisker-coated Al{sub 2}O{sub 3} joints was investigated by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. A continuous (Cu,Al){sub 3}Ti{sub 3}O layer formed against the alloy at lower bonding temperatures, and a complex transition zone bordering the whiskers was observed, which consisted of Ag nanoparticles, titanium oxides, TiB{sub 2}, (Cu,Al){sub 3}Ti{sub 3}O nanoparticles and possible Ag{sub 3}Al. As the bonding temperature increased, the Al{sub 2}O{sub 3}/AgCuTi interface was found to transform from whisker- to nanoparticle-strengthened composite region. Bend testmore » results revealed that both the whiskers grown on Al{sub 2}O{sub 3} and the dispersive nanoscale products in the alloy played positive roles in improving the joint properties. The maximum bend strength of the whisker-coated Al{sub 2}O{sub 3} joints was 313 MPa at the bonding temperature of 820 °C. - Highlights: • Al{sub 4}B{sub 2}O{sub 9}-whisker-coated Al{sub 2}O{sub 3} ceramics were bonded by AgCu–4.5 wt.%Ti alloy in vacuum. • Microstructures of whisker-coated Al{sub 2}O{sub 3} joints were investigated in detail. • Both whiskers and the dispersive nanoscale products can improve the joint properties. • The maximum bend strength of the whisker-coated Al{sub 2}O{sub 3} joints was 313 MPa.« less
  • Solvent-refined lignite (SRL) can be produced by treating lignite (not dried) with CO-H/sub 2/, donor solvent and high temperature. This reactive black solid softens at about 150/sup 0/C, is soluble in many organic solvents, is very low in ash and sulfur, and appears to be a good feedstock for further upgrading. Thus, a wide-ranging study was undertaken to determine the best reducing conditions for converting SRL to light distillable liquid fuels and/or chemical feedstocks. Batch autoclave studies were carried out in the temperature range of 375-450/sup 0/C, hydrogen pressure range of 1500-4500 psi, with catalysts Ni-Mo-Al/sub 2/O/sub 3/, Co-Mo-Al/sub 2/O/submore » 3/, Ni-W-Al/sub 2/O/sub 3/. Ni-W-SiO/sub 2/-Al/sub 2/O/sub 3/, SiO/sub 2/-Al/sub 2/O/sub 3/, Al/sub 2/O/sub 3/,SnCl/sub 2/, and presulfided catalysts Ni-Mo-Al/sub 2/O/sub 3/, Co-Mo-Al/sub 2/O/sub 3/, Ni-W-Al/sub 2/O/sub 3/. Varying amounts of the solvents tetrahydrofuran, tetralin, napthalene, and FS-120 petroleum fraction were also studied. Reductions without any solvent were studied too and were quite successful. The results were evaluated in terms of the amount of light liquids produced, deoxygenation, denitrification, hydrogen-carbon ratios, aromatic-aliphatic hydrogen ratios, and benzene solubility of unconverted material. Best results were obtained with a presulfided Ni-Mo-Al/sub 2/O/sub 3/ catalyst at 450/sup 0/C, operating pressure of about 3500 psi with a 1:1 SRL-tetralin solvent ratio (90 percent overall conversion, approx.20 percent light liquid (1), 15 percent light oil (2), 20 percent heavy oil (3 and 4), 10 percent unconverted). However, operating without any solvent also gave satisfactory results (88 percent overall conversion, 40 percent light liquid, 10 percent light oil, 10 percent heavy oil, 12 percent unconverted. Detailed gas chromatography-mass spectrometry (GC-MS) studies of selected liquid fractions indicate a high degree of aromaticity as tetralins, hydrophenanthrenes, and hydropyrenes.« less
  • An investigation on the structure of an ultrasonically cast nanocomposite of Al with 2 wt.% nano-sized Al{sub 2}O{sub 3} (average size {approx}10 nm) dispersoids showed that the nanocomposite was consisting of nearly continuous nano-alumina dispersed zones (NDZs) in the vicinity of the grain boundaries encapsulating Al{sub 2}O{sub 3} depleted zones (ADZs). The mechanical properties were investigated by nanoindentation and tensile tests. The nano-sized dispersoids caused a marginal increase in the elastic modulus, and a significant increase in the hardness ({approx}92%), and tensile strength ({approx}48%). Subsequent cold rolling to achieve a reduction ratio of 2 resulted in an appreciable increase inmore » the hardness due to change in morphology of the microstructure. Estimation of the strength on the basis of inter-particle spacing, which was measured by transmission electron microscopy, could not be accounted for on the basis of Orowan mechanism, and therefore, strengthening mechanisms like local climb and/or cross slip might have a role in this room temperature (0.32T{sub M}) deformation process.« less