Effect of Heat Treatment at (β+γ) Two Phase Region on Fracture Toughness in TiAl Intermetallic Compound

Makoto Hasegawa; Tomohiro Inui; Ivo Dlouhý

doi:10.4028/www.scientific.net/KEM.810.21

Paper Titles

Preface

Fracture Toughness and Charpy Impact Test of MIM Steels and Correlation of Results by K_IC- CVN Relationships
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Stress Distribution in Front of the Crack - Analytical Solutions vs. Numerical. Can the Differences be Minimized?
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Engineering Version of Local Approach to Fracture and its Application for RPV Lifetime Prediction
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Effect of Heat Treatment at (β+γ) Two Phase Region on Fracture Toughness in TiAl Intermetallic Compound
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Microstructural Change and Fracture Behavior under Different Heat Exposure Conditions on Thermal Barrier Coatings Deposited on TiAl Intermetallic Compound
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Fatigue Crack Growth Thresholds under Negative Stress Ratio for Aluminium Alloys
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Novel Methods for High-Cycle Fatigue Life Determination
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HomeKey Engineering MaterialsKey Engineering Materials Vol. 810Effect of Heat Treatment at (β+γ) Two Phase Region...

Effect of Heat Treatment at (β+γ) Two Phase Region on Fracture Toughness in TiAl Intermetallic Compound

Abstract:

Effects of holding temperature and time at (β+γ) two phase region on the microstructure of fully lamellar Ti-46Al-7Nb-0.7Cr-0.2Ni-0.1Si (mol%) intermetallic compounds are studies. Fully lamellar microstructure is observed after homogenization heat treatment for 3.6 ks at 1643 K (α single phase state). Fine β phased grains precipitate at fully lamellar structure after heat treatment of homogenized material at 1373 K. Holding the homogenized material for 72 ks at 1373 K decompose partially the lamellar structure. Heat treatment of homogenized material at 1273 K also precipitates the fine β phased grains in fully lamellar structure. In this temperature range, decomposition of lamellar structure is not observed up to 72 ks heat treatment. The toughness of homogenized material is ~ 15 MPa√m. Heat treatment of homogenized material at 1373 K and 1273 K for 3.6 ks indicates maximum fracture toughness in each temperature range. This may due to the precipitation of fine β phased grains. The fracture toughness decreases with the increase in heat treatment time up to 18 ks and/or 36 ks. Then, the value of fracture toughness became constant. Specimens heat treated at 1373 K for 36 ks and 72 ks indicate lower toughness than homogenized material. However, when the specimens are heat treated at 1273 K for 36 ks and 72 ks, the toughness is higher than that of homogenized material. This change is due to the decomposition of the lamellar structure.

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Periodical:

Key Engineering Materials (Volume 810)

Pages:

21-26

DOI:

https://doi.org/10.4028/www.scientific.net/KEM.810.21

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Online since:

July 2019

Authors:

Makoto Hasegawa*, Tomohiro Inui, Ivo Dlouhý

Keywords:

Fracture Toughness, Fully Lamellar, TiAl Intermetallic Compound, β Phase Precipitation

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