Effect of Cooling Rate on Microstructure of Two Kinds of High Nb Containing Tial Alloys

Effect of Cooling Rate on Microstructure of Two Kinds of High Nb Containing Tial Alloys

In this paper, high Nb-TiAl alloys with Cr and W additions were prepared by Vacuum induction melting method, and then were heat treated under three different cooling rates of slow cooling, furnace cooling and air cooling. The phase composition of the alloy was analyzed by X ray diffraction, and the...

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Bibliographic Details
Published in:IOP conference series. Materials Science and Engineering 2017-09, Vol.230 (1), p.12048
Main Authors: Chai, L H, Feng, Z Y, Xiang, Z L, Cui, Y S, Zhou, F, Chen, Z Y
Format: Article
Language:eng
Subjects:
Air cooling
Alloying
Alloys
Beta phase
Chromium base alloys
Cooling effects
Cooling rate
Grain boundaries
Grain size
Heat treating
Heat treatment
Lamellar structure
Microstructure
Niobium
Optical microscopes
Phase composition
Titanium base alloys
Tungsten
Vacuum induction melting
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Summary:In this paper, high Nb-TiAl alloys with Cr and W additions were prepared by Vacuum induction melting method, and then were heat treated under three different cooling rates of slow cooling, furnace cooling and air cooling. The phase composition of the alloy was analyzed by X ray diffraction, and the microstructure of the alloy was observed by optical microscope (OM), scanning electron microscope (SEM) and energy dispersive analyzer. The results show that the microstructure of Ti45Al8Nb0.2Cr and Ti45Al8Nb0.2W are fully lamellar structure with the main phase composition of α+γ after 3 different heat treatment conditions. The grain size of the two alloys decreases with decreasing of cooling rate, and the grain size of the alloyed with Cr alloy is smaller than that of the alloyed with W alloy. Most of the original massive β phase at grain boundaries and lamellar interfaces dissolved after heat treatment, and the transformation of β phase is easier for Ti45Al8Nb0.2Cr.
ISSN:1757-8981
1757-899X