Effect of heating rate inα+γdual-phase field on lamellar microstructure and creep resistance of a TiAl alloy

2005 ◽  
Vol 96 (6) ◽  
pp. 584-588
Author(s):  
Kouichi Maruyama ◽  
Jun Matsuda ◽  
Hanliang Zhu
Keyword(s):  
Heating Rate ◽  
Phase Field ◽  
Creep Resistance ◽  
Tial Alloy ◽  
Lamellar Microstructure

A TEM study of the influence of microstructure on the superplastic behavior of a U-5.8 wt.% Nb alloy

1986 ◽  
Vol 44 ◽  
pp. 568-569
Author(s):  
G. Mackiewicz Ludtka
Keyword(s):  
Grain Size ◽  
Heating Rate ◽  
Phase Field ◽  
Single Phase ◽  
Superplastic Behavior ◽  
Two Phase ◽  
Single Phase Field

Historically, metals exhibit superplasticity only while forming in a two-phase field because a two-phase microstructure helps ensure a fine, stable grain size. In the U-5.8 Nb alloy, superplastici ty exists for up to 2 h in the single phase field (γ1) at 670°C. This is above the equilibrium monotectoid temperature of 647°C. Utilizing dilatometry, the superplastic (SP) U-5.8 Nb alloy requires superheating to 658°C to initiate the α+γ2 → γ1 transformation at a heating rate of 1.5°C/s. Hence, the U-5.8 Nb alloy exhibits an anomolous superplastic behavior.

Effect of Heat Treatment on the Microstructure and Property of TiAl Alloys Prepared by Gas Atomization Powders

2013 ◽  
Vol 747-748 ◽  
pp. 497-501
Author(s):  
Na Liu ◽  
Zhou Li ◽  
Guo Qing Zhang ◽  
Hua Yuan ◽  
Wen Yong Xu ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Heat Treatment Temperature ◽  
Tial Alloy ◽  
Lamellar Microstructure ◽  
Treatment Temperature ◽  
Gas Atomization ◽  
Thermally Induced ◽  
Heat Treated ◽  
Fine Duplex ◽  
Step Heat Treatment

Powder metallurgical TiAl alloy was fabricated by gas atomization powders, and the effect of heat treatment temperature on the microstructure evolution and room tensile properties of PM TiAl alloy was investigated. The uniform fine duplex microstructure was formed in PM TiAl based alloy after being heat treated at 1250/2h followed by furnace cooling (FC)+ 900/6h (FC). When the first step heat treatment temperature was improved to 1360/1h, the near lamellar microstructure was achieved. The ductility of the alloy after heat treatment improved markedly to 1.2% and 0.6%, but the tensile strength decreased to 570MPa and 600MPa compared to 655MPa of as-HIP TiAl alloy. Post heat treatment at the higher temperature in the alpha plus gamma field would regenerate thermally induced porosity (TIP).

Martensite in a TiAl alloy quenched from beta phase field

2015 ◽  
Vol 56 ◽  
pp. 87-95 ◽  
Author(s):  
D. Hu ◽  
H. Jiang
Keyword(s):  
Phase Field ◽  
Tial Alloy ◽  
Beta Phase

Microstructure of Rolled Ti-46.5Al-4(CrNb,Ta,B)

1998 ◽  
Vol 552 ◽  
Author(s):  
B. J. Inkson ◽  
H. Clemens
Keyword(s):  
Phase Field ◽  
Boron Content ◽  
Sheet Material ◽  
Lamellar Microstructure ◽  
Heat Treatments ◽  
Grain Structure ◽  
Α Phase ◽  
Heat Treated ◽  
B2 Phase ◽  
Fully Lamellar

ABSTRACTAn industrial Ti-46.5A1–4(CrNb,Ta) alloy, with and without boron additions, has been successfully rolled to sheet 1.5mm thick. The microstructure of the sheet material has been characterised as a function of boron content and subsequent heat treatments. It is observed that rod-like (Ti-Ta)B precipitates are effective in refining the grain structure in both as-rolled and subsequently heat treated material. As-rolled microstructures rapidly cooled from the α + γ phase field contain unstable α2, which transforms to B2 phase on annealing below the α + γ tranus. Annealing in the α-phase field can result in a designed fully lamellar microstructure.

Creep Deformation of a Fully Lamellar Gamma Based Titanium Aluminide Alloy

1996 ◽  
Vol 460 ◽  
Author(s):  
F. Herrouin ◽  
P. Bowen ◽  
I. P. Jones
Keyword(s):  
Gas Turbine ◽  
Creep Deformation ◽  
Titanium Aluminide ◽  
Creep Resistance ◽  
Tial Alloy ◽  
Operating Conditions ◽  
Two Phase ◽  
Titanium Aluminide Alloy ◽  
Aero Engine ◽  
Fully Lamellar

ABSTRACTA complex two phase γ-TiAl alloy, Ti-47Al-lCr-1Mn-2Ta-0.2Si (at.%) in a fully lamellar condition, has been creep tested at a stress of 200MPa and a temperature of 700°C. This simulates the in-service operating conditions for several potential gas turbine aero engine applications where creep resistance is a design limiting material property. The results have indicate that reduction in lamellae thickness and avoidance of feathery type microstructures contribute to improved creep resistance.

Crystallography of phase transformation during quenching from β phase field of a V-rich TiAl alloy

2018 ◽  
Vol 54 (2) ◽  
pp. 1844-1856 ◽  
Author(s):  
Yi Chen ◽  
Hongchao Kou ◽  
Liang Cheng ◽  
Ke Hua ◽  
Lingyan Sun ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Phase Field ◽  
Tial Alloy ◽  
Β Phase

Influence of Microstructure and Stress Ratio on Fatigue Crack Propagation in TiAl Alloy

2014 ◽  
Vol 881-883 ◽  
pp. 1330-1333 ◽  
Author(s):  
Yan Rui Zuo ◽  
Zhi Yuan Rui ◽  
Rui Cheng Feng ◽  
De Chun Luo ◽  
Chang Feng Yan
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Stress Ratio ◽  
Tial Alloy ◽  
Lamellar Microstructure ◽  
Propagation Resistance ◽  
Crack Propagation Resistance ◽  
Stress Ratios ◽  
Fully Lamellar

Based on the fatigue crack propagation experiments did by A.-L. Gloanec et al., the fatigue crack propagation rates of TiAl alloy of two processing routes, namely casting and PM, and stress ratios had been tested, in order to find out the effects of microstructure and stress ratio. An improved fatigue crack propagation formula for region Ⅱ (the expansion region) was derived according to Paris formula. The specific values of the constants in the formula were calculated. Fatigue crack propagation resistance of nearly fully lamellar microstructure is superior to that of equiaxed γ grain. The experimental results present that both microstructure and stress ratio has a significant influence on fatigue crack growth rate.

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