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Title: Interdiffusion in ? (fcc) Ni-Cr-X (X=Al, Si, Ge or Pd) Alloys at 900?C

Abstract

Interdiffusion in Ni-Cr (fcc phase) alloys with small additions of Al, Si, Ge, or Pd was investigated using solid-to-solid diffusion couples. Ni-Cr-X alloys having compositions of Ni- 22at.%Cr, Ni-21at.%Cr-6.2at.%Al, Ni-22at.%Cr-4.0at.%Si, Ni-22at.%Cr-1.6at.%Ge and Ni- 22at.%Cr-1.6at.%Pd were manufactured by arc-casting. The diffusion couples were assembled in an Invar steel jig, encapsulated in Ar after several hydrogen purges, and annealed at 900 C in a three-zone tube furnace for 168 hours. Experimental concentration profiles were determined from polished cross-section of these couples by using electron probe microanalysis with pure element standards. Interdiffusion fluxes of individual components were calculated directly from the experimental concentration profiles, and the moments of interdiffusion fluxes were examined to determine average ternary interdiffusion coefficients. Effects of ternary alloying additions on the diffusional behavior of Ni-Cr-X alloys are presented in the light of the diffusional interactions and the formation of a protective Cr2O3 scale

Authors:
 [1];  [2];  [1]
  1. University of Central Florida
  2. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
FE USDOE - Office of Fossil Energy (FE)
OSTI Identifier:
930777
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Phase Equilibria and Diffusion; Journal Volume: 27; Journal Issue: 6
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 08 HYDROGEN; ALLOYS; DIFFUSION; ELECTRON PROBES; FURNACES; HYDROGEN; INVAR; MICROANALYSIS; STEELS

Citation Formats

Garimella, N, Brady, Michael P, and Sohn, Yong Ho. Interdiffusion in ? (fcc) Ni-Cr-X (X=Al, Si, Ge or Pd) Alloys at 900?C. United States: N. p., 2006. Web. doi:10.1007/BF02736570.
Garimella, N, Brady, Michael P, & Sohn, Yong Ho. Interdiffusion in ? (fcc) Ni-Cr-X (X=Al, Si, Ge or Pd) Alloys at 900?C. United States. doi:10.1007/BF02736570.
Garimella, N, Brady, Michael P, and Sohn, Yong Ho. Sun . "Interdiffusion in ? (fcc) Ni-Cr-X (X=Al, Si, Ge or Pd) Alloys at 900?C". United States. doi:10.1007/BF02736570.
@article{osti_930777,
title = {Interdiffusion in ? (fcc) Ni-Cr-X (X=Al, Si, Ge or Pd) Alloys at 900?C},
author = {Garimella, N and Brady, Michael P and Sohn, Yong Ho},
abstractNote = {Interdiffusion in Ni-Cr (fcc phase) alloys with small additions of Al, Si, Ge, or Pd was investigated using solid-to-solid diffusion couples. Ni-Cr-X alloys having compositions of Ni- 22at.%Cr, Ni-21at.%Cr-6.2at.%Al, Ni-22at.%Cr-4.0at.%Si, Ni-22at.%Cr-1.6at.%Ge and Ni- 22at.%Cr-1.6at.%Pd were manufactured by arc-casting. The diffusion couples were assembled in an Invar steel jig, encapsulated in Ar after several hydrogen purges, and annealed at 900 C in a three-zone tube furnace for 168 hours. Experimental concentration profiles were determined from polished cross-section of these couples by using electron probe microanalysis with pure element standards. Interdiffusion fluxes of individual components were calculated directly from the experimental concentration profiles, and the moments of interdiffusion fluxes were examined to determine average ternary interdiffusion coefficients. Effects of ternary alloying additions on the diffusional behavior of Ni-Cr-X alloys are presented in the light of the diffusional interactions and the formation of a protective Cr2O3 scale},
doi = {10.1007/BF02736570},
journal = {Journal of Phase Equilibria and Diffusion},
number = 6,
volume = 27,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • Interdiffusion at 700 aC for Ni-22at.%Cr (fcc ^ phase) alloys with small additions of Al, Si, Ge, or Pd was examined using solid-to-solid diffusion couples. Rods of Ni-22at.%Cr, Ni-21at.%Cr-6.2at.%Al, Ni-22at.%Cr-4.0at.%Si, Ni-22at.%Cr-1.6at.%Ge and Ni-22at.%Cr-1.6at.%Pd alloys were cast using arc-melt and homogenized at 900 aC for 168 hours. The diffusion couples were assembled with alloy disks in Invar steel jig, encapsulated in Argon after several hydrogen flushes, and annealed at 700 XC for 720 hours. Experimental concentration profiles were determined from polished cross-sections by using electron probe microanalysis with pure standards of Ni, Cr, Al, Si, Ge and Pd. Interdiffusion fluxes ofmore » individual components were calculated directly from the experimental concentration profiles, and the moments of interdiffusion fluxes were examined to determine average ternary interdiffusion coefficients. Effects of ternary alloying additions on the interdiffusional behavior of Ni-Cr-X alloys at 700 XC are presented in the light of the diffusional interactions and the formation of protective Cr2O3 scale.« less
  • Interdiffusion in Fe-Ni-Cr (fcc phase) alloys with small additions of Si and Ge at 900 C was studied using solid-to-solid diffusion couples. Alloy rods of Fe-24 at.%Ni, Fe-24 at.%Ni- 22at.%Cr, Fe-24 at.%Ni-22at.%Cr-4at.%Si and Fe-24 at.%Ni-22at.%Cr-1.7at.%Ge were cast using arc-melt, and homogenized at 900 C for 168 hours. Sectioned alloy disks from the rods were polished, and diffusion couples were assembled with in Invar steel jig, encapsulated in Argon after several hydrogen flushes, and annealed atz 900 C for 168 hours. Polished cross-sections of the diffusion couples were characterized to determine experimental concentration profiles using electron probe microanalysis with pure elementalmore » standards. Interdiffusion fluxes of individual components were calculated directly from the experimental concentration profiles, and the moments of interdiffusion flux profiles were examined to determine the average ternary and quaternary interdiffusion coefficients. Effects of alloying additions on the interdiffusional behavior of Fe-Ni- Cr-X alloys at 900 C are presented with due consideration for the formation of protective Cr2O3 scale.« less
  • A novel, low-expansion experimental Ni-Cr-Al-Ti-Si bond-coating alloy was investigated in the as-cast state concerning its phase stability, oxidation resistance in air, and interdiffusion with single-crystal IN-100 at 900, 1000, and 1100{degrees}C. Isothermal oxidative thermogravimetry was employed up to 500 hr. Interdiffusion was compared to a commercial Ni-Co-CR-Al-Y alloy in IN-100. Oxidized Ni-Cr-Al-Ti-Si specimens and diffusion couples were characterized by metallography, SEM, EDX, XRD, and XRF. The Ni-Crl-Al-Ti-Si alloy provides good oxidation resistance in air at least up to 1000{degrees}C. The alloy is an alumina former. Due to its coarse microstructure, other oxides (e.g., rutile) may form and considerably dominate themore » oxidation behavior. The kinetics of oxidation were correlated with temperature, formation of phases, and morphology of oxides. Interdiffusion fluxes between Ni-Cr-Al-Ti-Si and IN-100 were mainly directed to the superalloy. They were faster than in Ni-Co-Cr-Al-Y/IN-100 diffusion couples.« less
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  • No abstract prepared.