scholarly journals Influence of α-Phase Field Heat Treatment on the Tensile and Primary Creep Resistance of a Powder Metallurgical Processed Ti-45Al-5Nb-0.2B-0.2C Titanium Aluminide Alloy

2017 ◽  
Vol 899 ◽  
pp. 418-423
Author(s):  
Rafael Paiotti Marcondes Guimarães ◽  
Juliano Soyama ◽  
Thomas Ebel ◽  
Márcio C. Fredel ◽  
Florian Pyczak
Keyword(s):  
Heat Treatment ◽  
Colony Size ◽  
Titanium Aluminide ◽  
Creep Resistance ◽  
Titanium Aluminides ◽  
Primary Creep ◽  
Heat Treatments ◽  
Titanium Aluminide Alloy ◽  
Metallurgical Processing ◽  
Microstructure Parameters

In powder metallurgical processing the sintering process, as well as heat treatments, can drastically influence microstructure formation. In the case of γ-titanium aluminides, it is critical to achieve certain microstructure parameters, such as colony size, porosity and grain boundary morphology in order to obtain appropriate mechanical properties. In this study, the effect of a heat treatment implemented after sintering with the objective of varying the colony size was investigated. Specimens of Ti-45Al-5Nb-0.2B-0.2C prepared by metal injection moulding and uniaxial pressing of feedstock were used to evaluate the tensile and creep properties. Heat treatments conducted at 1350 and 1400 °C for 3 h led to colony sizes of approximately 100 and 200 μm, respectively. Classically, there is an inverse relationship between grain size and creep resistance, nonetheless, for γ-titanium aluminides, the morphology of the colony boundaries was also found to play a role. The larger colony sizes achieved with the heat treatments did not improve the primary creep resistance, which was explained by the change in the morphology of the colony boundaries as they became larger.

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.

Study on Processing of Titanium Aluminide Alloy Using Electrical Discharge Machining

2014 ◽  
Vol 657 ◽  
pp. 311-315 ◽  
Author(s):  
Mihai Trifănescu ◽  
Alexandra Banu ◽  
Aurelian Vişan ◽  
Nicolae Ionescu ◽  
Alexandru Paraschiv ◽  
...  
Keyword(s):  
Titanium Aluminide ◽  
Electrical Discharge ◽  
Titanium Aluminides ◽  
Electrical Discharge Machining ◽  
Continuous Extension ◽  
Experimental Measurements ◽  
Wire Edm ◽  
Reverse Polarity ◽  
Technological Characteristics ◽  
Titanium Aluminide Alloy

Currently there is a continuous extension of application areas of titanium aluminides but their processing encounters a number of difficulties such as the precision of machining and modifying the properties of the surface layer. In the specialist literature [1, 2, 4, 7] different authors address the processing of these materials by conventional methods. In this context, this paper aims at finding the optimal regimes for the electrical discharge machining (EDM) of titanium aluminides Ti-40Al-5NB-3V and provides the analysis of the process parameters effect on cutting through wire EDM technological characteristics. In the case of wire EDM a relatively good output has been obtained as well as very good roughness of the processed surfaces. On the contrary, when considering the die sinking edm, due to very small output, several experimental measurements were performed on three machines – Sodick, ONA and ELER. Based on the experimental data, it has been established that the best output is to be obtained by reverse polarity machining.

Effects of Heat Treatment on a High-Pressure Die-Cast Mg-La-Y Alloy

2011 ◽  
Vol 690 ◽  
pp. 210-213 ◽  
Author(s):  
Serge Gavras ◽  
Su Ming Zhu ◽  
Mark A. Easton ◽  
Mark A. Gibson ◽  
Jian Feng Nie
Keyword(s):  
Heat Treatment ◽  
High Pressure ◽  
Creep Resistance ◽  
Solution Treatment ◽  
Dislocation Motion ◽  
Heat Treatments ◽  
Dimensional Changes ◽  
Heat Treated ◽  
Die Cast ◽  
Solute Atoms

In this study effects of heat treatments on the creep resistance at 177°C/90MPa of a high-pressure die-cast Mg-2.70La-1.50Y (wt.%) alloy were examined. It was found that ageing at 160°C for 24 h (T5) or a solution treatment at 520°C for 1 h (T4) improved creep resistance and caused no blistering on the surface or dimensional changes to the die-cast specimens. TEM was used to characterize the microstructures of heat-treated samples. Improvements to creep resistance might be attributed to the pinning or otherwise retarding of dislocation motion by precipitates and/or solute atoms during creep.

Solution and Precipitation Hardening in Carbon-Doped Two-Phase γ-Titanium Aluminides

1996 ◽  
Vol 460 ◽  
Author(s):  
F. Appel ◽  
U. Christoph ◽  
R. Wagner
Keyword(s):  
High Temperature ◽  
Titanium Aluminide ◽  
Precipitation Hardening ◽  
Titanium Aluminides ◽  
Activation Parameters ◽  
High Temperature Strength ◽  
Thermal Treatments ◽  
Two Phase ◽  
Carbon Doped ◽  
Titanium Aluminide Alloy

ABSTRACTA two-phase titanium aluminide alloy was systematically doped with carbon to improve its high temperature strength. Solid solutions and precipitates of carbon were formed by different thermal treatments. A fine dispersion of perovskite precipitates was found to be very effective for improving the high temperature strength and creep resistance of the material. The strengthening mechanisms were characterized by flow stresses and activation parameters. The investigations were accompanied by electron microscope observation of the defect structure which was generated during deformation. Special attention was paid on the interaction mechanisms of perfect and twinning dislocations with the carbide precipitates.

Assessing the Influence of Heat Treatments on γ-TiAl Joints

2006 ◽  
Vol 514-516 ◽  
pp. 1333-1337 ◽  
Author(s):  
Anibal Guedes ◽  
Ana Maria Pires Pinto ◽  
Manuel F. Vieira ◽  
Filomena Viana
Keyword(s):  
Titanium Aluminide ◽  
Tial Alloy ◽  
Braze Alloy ◽  
Heat Treating ◽  
Heat Treatments ◽  
Interfacial Zone ◽  
Alloy Foil ◽  
Heat Treated ◽  
Titanium Aluminide Alloy ◽  
Brazed Joints

The heat treatment of γ-TiAl alloy (Ti-47Al-2Cr-2Nb (at.%)) diffusion brazed joints was investigated. Joining was performed using a Ti/Ni/Ti clad-laminated braze alloy foil at 1050 and 1150°C with a dwell time of 10 minutes. The joints were subsequently heat treated at 1250 and 1350°C for 240 and 30 minutes, respectively. The microstructure and the chemical composition of the interfaces were analysed by scanning electron microscopy (SEM) and by energy dispersive X-ray spectroscopy (EDS), respectively. Microhardness tests performed across the interface were used to roughly predict the mechanical behaviour of the as-diffusion brazed and of the heat treated joints. Diffusion brazing produced interfaces with two distinct layers essentially composed of α2-Ti3Al and of TiNiAl; γ-TiAl was also detected for joining at 1150°C. After heat treating, the as-diffusion brazed microstructure of the interface was completely replaced by a mixture essentially composed of γ-TiAl and α2–Ti3Al single phase grains and of (α2 + γ) lamellar grains. Microhardness tests showed that the hardness of the as-diffusion brazed interfaces, which ranges from 567 to 844 HV (15 gf), is significantly higher than that of the titanium aluminide alloy (272 HV). All post-joining heat treatments lowered substantially the hardness of the interface, as the hardness of the main phases detected at the interfacial zone after heat treating the joints is comprised between 296 and 414 HV.

The Effect of Molybdenum on the Creep Behavior of Orthorhombic Titanium Aluminides

2002 ◽  
Author(s):  
Dominique A. Shepherd ◽  
Vijay K. Vasudevan
Keyword(s):  
Creep Behavior ◽  
Titanium Aluminide ◽  
Creep Resistance ◽  
Titanium Aluminides ◽  
Tensile Creep ◽  
Atomic Fraction ◽  
Beta Transus ◽  
Creep Properties ◽  
Orthorhombic Titanium ◽  
Transus Temperature

The effect of molybdenum additions on the creep properties of two orthorhombic titanium aluminide materials, Ti-22Al-26Nb and Ti-22Al-24.5Nb-1.5Mo (% atomic fraction), has been investigated. Heat treatments below the beta transus temperature followed by a 16-hour ageing treatment produced similar microstructures. Using the similar microstructures (consisting of O laths in a B2 matrix with α2 dispersed at B2 grain boundaries) for the two compositions, tensile creep testing was conducted under stresses of 68 MPa, 160 MPa, and 197 MPa at temperatures of 590 °C and 760 °C. The creep results demonstrated the favorable effects of Mo on creep resistance in these orthorhombic titanium aluminides. Due to similar microstructures, results also suggested that improvements have been substructural, rather than purely microstructural, in nature.

Chemical Synthesis and Characterization of Nanostructured Titanium Aluminide

1994 ◽  
Vol 351 ◽  
Author(s):  
S.T. Schwab ◽  
P.P. Paul ◽  
Y-M. Pan
Keyword(s):  
Heat Treatment ◽  
Chemical Analysis ◽  
Chemical Synthesis ◽  
Titanium Aluminide ◽  
Titanium Aluminides ◽  
Synthesis And Characterization ◽  
Nanostructured Titanium ◽  
Nanosize Particles

ABSTRACTAlthough plagued by a lack of ductility, titanium aluminides are among the most promising intermetallics under development. Significant improvements in ductility may be obtained from nanostructured intermetallics. Nanosize particles of TiAl3 have been prepared by heat-treatment of chemically synthesized precursor (compound 1). Nanosized TiAl3 has been characterized by chemical analysis, XRD, EDS, NMR, and HREM.

Heat treatment behavior of can-forged titanium aluminide alloy in (α+γ) region

1998 ◽  
Vol 5 (2) ◽  
pp. 86-89 ◽  
Author(s):  
Yong Liu ◽  
Baiyun Huang ◽  
Yuehui He ◽  
Zhongyong Deng
Keyword(s):  
Heat Treatment ◽  
Titanium Aluminide ◽  
Titanium Aluminide Alloy

scholarly journals Evolution of Elevated-Temperature Strength and Creep Resistance during Multi-Step Heat Treatments in Al-Mn-Mg Alloy

2018 ◽  
Author(s):  
G. S. Wang ◽  
K. Liu ◽  
S. L. Wang
Keyword(s):  
Heat Treatment ◽  
Elevated Temperature ◽  
Creep Resistance ◽  
Threshold Stress ◽  
Heat Treatments ◽  
Mg Alloy ◽  
Elevated Temperature Strength ◽  
Lower Temperature ◽  
Increasing Temperature ◽  
Step Heat Treatment

Present work has systematically investigated the evolution of dispersoid and elevated-temperature properties including the strength and creep resistance during the various multi-step heat treatments in Al-Mn-Mg 3004 alloys. Results show that only α-Al(MnFe)Si dispersoid is observed in the studied temperature range (up to 625°C) and it coarsens with increasing temperature to 500°C but dissolves at 625°C. The evolution of elevated-temperature strength and creep resistance is greatly related to the temperature of each step during the multi-step heat treatments. Generally, lower temperature at the first-step heat treatment leads to higher properties while the properties decrease with increasing temperature of last-step heat treatment. Suitable models have been introduced to explain the evolution of strength and the creep threshold stress at elevated-temperature during the various heat treatments.

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