Effect of tungsten concentration on microstructures of Co-10Ni-6Al-(0,2,4,6)W-6Ti (at%) cobalt-based superalloys

Peter J. Bocchini*, Chantal K. Sudbrack, Daniel J. Sauza, Ronald D. Noebe, David N Seidman, David C Dunand

*Corresponding author for this work

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

The effects of reducing the W concentration (and concomitantly mass density) of Co-10Ni-6Al-xW-6Ti at% Co-based superalloys, with a γ(f.c.c.) plus γ′(L12) microstructure, is investigated for a series of alloys with W concentrations of 6 at% (baseline alloy), 4 and 2 at% (W-reduced) and 0 at% (W-free). The γ′(L12) solvus temperature decreases strongly (by 46 °C per 1 at% reduction in W), while the liquidus and solvus temperatures decrease mildly (3–5 °C per 1 at% W reduction) as measured by differential scanning calorimetry. Scanning electron microscopy was used to image phase formation in all alloys. When aging at 900 or 1000 °C for 256 h, the W reduction does not result in the appearance of additional phases within the grains beyond the γ(f.c.c.) and γ′(L12) phases present in the original alloy. Grain-boundary precipitates are present for all alloy compositions: W-rich or W-free precipitates after aging at 1000 °C, and coarsened γ′(L12) precipitates after aging at 900 °C. The composition of grain boundary precipitates were measured with energy-dispersive X-ray spectroscopy. Vickers microhardness values decrease with decreasing W content, due to a reduction in γ′(L12) precipitation and reduced solid-solution strengthening.

Original languageEnglish (US)
Pages (from-to)481-486
Number of pages6
JournalMaterials Science and Engineering A
Volume700
DOIs
StatePublished - Jul 17 2017

Fingerprint

Tungsten
heat resistant alloys
Cobalt
Superalloys
tungsten
cobalt
Precipitates
precipitates
microstructure
Microstructure
Aging of materials
Grain boundaries
grain boundaries
liquidus
Chemical analysis
Microhardness
microhardness
Differential scanning calorimetry
Solid solutions
solid solutions

Keywords

  • Cobalt alloys
  • Intermetallic
  • L1, grain boundary
  • Superalloy

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

Cite this

@article{98dddc2da2604347b2b139c81ca4a15e,
title = "Effect of tungsten concentration on microstructures of Co-10Ni-6Al-(0,2,4,6)W-6Ti (at{\%}) cobalt-based superalloys",
abstract = "The effects of reducing the W concentration (and concomitantly mass density) of Co-10Ni-6Al-xW-6Ti at{\%} Co-based superalloys, with a γ(f.c.c.) plus γ′(L12) microstructure, is investigated for a series of alloys with W concentrations of 6 at{\%} (baseline alloy), 4 and 2 at{\%} (W-reduced) and 0 at{\%} (W-free). The γ′(L12) solvus temperature decreases strongly (by 46 °C per 1 at{\%} reduction in W), while the liquidus and solvus temperatures decrease mildly (3–5 °C per 1 at{\%} W reduction) as measured by differential scanning calorimetry. Scanning electron microscopy was used to image phase formation in all alloys. When aging at 900 or 1000 °C for 256 h, the W reduction does not result in the appearance of additional phases within the grains beyond the γ(f.c.c.) and γ′(L12) phases present in the original alloy. Grain-boundary precipitates are present for all alloy compositions: W-rich or W-free precipitates after aging at 1000 °C, and coarsened γ′(L12) precipitates after aging at 900 °C. The composition of grain boundary precipitates were measured with energy-dispersive X-ray spectroscopy. Vickers microhardness values decrease with decreasing W content, due to a reduction in γ′(L12) precipitation and reduced solid-solution strengthening.",
keywords = "Cobalt alloys, Intermetallic, L1, grain boundary, Superalloy",
author = "Bocchini, {Peter J.} and Sudbrack, {Chantal K.} and Sauza, {Daniel J.} and Noebe, {Ronald D.} and Seidman, {David N} and Dunand, {David C}",
year = "2017",
month = "7",
day = "17",
doi = "10.1016/j.msea.2017.06.018",
language = "English (US)",
volume = "700",
pages = "481--486",
journal = "Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing",
issn = "0921-5093",
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}

Effect of tungsten concentration on microstructures of Co-10Ni-6Al-(0,2,4,6)W-6Ti (at%) cobalt-based superalloys. / Bocchini, Peter J.; Sudbrack, Chantal K.; Sauza, Daniel J.; Noebe, Ronald D.; Seidman, David N; Dunand, David C.

In: Materials Science and Engineering A, Vol. 700, 17.07.2017, p. 481-486.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Effect of tungsten concentration on microstructures of Co-10Ni-6Al-(0,2,4,6)W-6Ti (at%) cobalt-based superalloys

AU - Bocchini, Peter J.

AU - Sudbrack, Chantal K.

AU - Sauza, Daniel J.

AU - Noebe, Ronald D.

AU - Seidman, David N

AU - Dunand, David C

PY - 2017/7/17

Y1 - 2017/7/17

N2 - The effects of reducing the W concentration (and concomitantly mass density) of Co-10Ni-6Al-xW-6Ti at% Co-based superalloys, with a γ(f.c.c.) plus γ′(L12) microstructure, is investigated for a series of alloys with W concentrations of 6 at% (baseline alloy), 4 and 2 at% (W-reduced) and 0 at% (W-free). The γ′(L12) solvus temperature decreases strongly (by 46 °C per 1 at% reduction in W), while the liquidus and solvus temperatures decrease mildly (3–5 °C per 1 at% W reduction) as measured by differential scanning calorimetry. Scanning electron microscopy was used to image phase formation in all alloys. When aging at 900 or 1000 °C for 256 h, the W reduction does not result in the appearance of additional phases within the grains beyond the γ(f.c.c.) and γ′(L12) phases present in the original alloy. Grain-boundary precipitates are present for all alloy compositions: W-rich or W-free precipitates after aging at 1000 °C, and coarsened γ′(L12) precipitates after aging at 900 °C. The composition of grain boundary precipitates were measured with energy-dispersive X-ray spectroscopy. Vickers microhardness values decrease with decreasing W content, due to a reduction in γ′(L12) precipitation and reduced solid-solution strengthening.

AB - The effects of reducing the W concentration (and concomitantly mass density) of Co-10Ni-6Al-xW-6Ti at% Co-based superalloys, with a γ(f.c.c.) plus γ′(L12) microstructure, is investigated for a series of alloys with W concentrations of 6 at% (baseline alloy), 4 and 2 at% (W-reduced) and 0 at% (W-free). The γ′(L12) solvus temperature decreases strongly (by 46 °C per 1 at% reduction in W), while the liquidus and solvus temperatures decrease mildly (3–5 °C per 1 at% W reduction) as measured by differential scanning calorimetry. Scanning electron microscopy was used to image phase formation in all alloys. When aging at 900 or 1000 °C for 256 h, the W reduction does not result in the appearance of additional phases within the grains beyond the γ(f.c.c.) and γ′(L12) phases present in the original alloy. Grain-boundary precipitates are present for all alloy compositions: W-rich or W-free precipitates after aging at 1000 °C, and coarsened γ′(L12) precipitates after aging at 900 °C. The composition of grain boundary precipitates were measured with energy-dispersive X-ray spectroscopy. Vickers microhardness values decrease with decreasing W content, due to a reduction in γ′(L12) precipitation and reduced solid-solution strengthening.

KW - Cobalt alloys

KW - Intermetallic

KW - L1, grain boundary

KW - Superalloy

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U2 - 10.1016/j.msea.2017.06.018

DO - 10.1016/j.msea.2017.06.018

M3 - Article

VL - 700

SP - 481

EP - 486

JO - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing

JF - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing

SN - 0921-5093

ER -