Transformations of Phases in Titanium Alloy after High Temperature Hydrogen Treatment

2013 ◽  
Vol 197 ◽  
pp. 168-173 ◽  
Author(s):  
Maria Sozańska
Keyword(s):  
Titanium Alloy ◽  
High Temperature ◽  
Hydrogen Gas ◽  
Hydrogen Treatment ◽  
Two Phase ◽  
Gas Atmosphere ◽  
Three Stages ◽  
Grade 3 ◽  
Titanium Grade ◽  
Positive Nature

Positive nature of the effects of hydrogen on the properties of titanium alloys is manifested in the high temperature hydrogen treatment (HTM - Hydrogen Treatment of Materials), where hydrogen is temporary alloying component. The paper presents the results of the possibilities of hydrogen using as a temporary alloying element in Ti-6Al-4V alloy and titanium Grade 3. Treatment of hydrogen alloy consisted of three stages: hydrogenation in hydrogen gas atmosphere at 650°C, a cyclic hydrogen-treatment (3 cycles 850 °C to 250 °C) and a dehydrogenation in vacuum (550°C). It was shown that hydrogen affects appreciably changes the microstructure of surface layer of the tested titanium alloy. The aim of this work is to determine the effect of hydrogen on the two-phase microstructure in Ti-6Al-4V alloy and Grade 3 titanium and hardness after high temperature hydrogen treatment.

Effect of a High-Temperature Hydrogen Treatment on a Microstructure and Surface Fracture in Titanium Ti-6Al-4V Alloy

2012 ◽  
Vol 191 ◽  
pp. 243-248
Author(s):  
Maria Sozańska
Keyword(s):  
Titanium Alloy ◽  
High Temperature ◽  
Titanium Alloys ◽  
Hydrogen Gas ◽  
Hydrogen Treatment ◽  
Surface Fracture ◽  
Two Phase ◽  
Hydrogen Corrosion ◽  
Gas Atmosphere ◽  
Three Stages

Influence of hydrogen on the structure of titanium alloys is a complex phenomenon, depending on the circumstances, may be negative or positive [1,2]. The presence of hydrogen in titanium alloys usually results in degradation of their microstructure and properties, as well promote some undesirable effects such as hydrogen corrosion and hydrogen embrittlement [3]. Positive nature of the effects of hydrogen on the properties of titanium alloys is manifested in the high temperature hydrogen treatment (HTM - Hydrogen Treatment of Materials), where hydrogen is temporary alloying component [4-9]. This is possible because of the high values of diffusion coefficients can be easily introduced into the titanium and it just as easily removed. Titanium and its alloys show the absorbability of almost 60 at. % of hydrogen at 600°C. The limit hydrogen of solubility in Tiα is very low and does not exceed 0.05 at. % at room temperature. The limit hydrogen of solubility in Tiβ is much higher and its maximum value is 48 at. %. Since the beginning of the titanium industry, a great deal of attention has been paid to control the hydrogen content at titanium products – above 0.2 ppm. The paper presents the results of the possibilities of hydrogen using as a temporary alloying element in Ti-6Al-4V alloy. Treatment of hydrogen alloy consisted of three stages: hydrogenation in hydrogen gas atmosphere at 650 °C, a cyclic hydrogen-treatment (3 cycles 650 °C to 250 °C) and a dehydrogenation in vacuum (550 °C). It was shown that hydrogen affects appreciably changes the microstructure of surface layer of the tested titanium alloy. The aim of this study is thus to determine the effect of hydrogen on the two-phase microstructure, hardness, and surface fracture of the titanium alloy Ti-6Al-4V due to high-temperature hydrogen treatment.

Positive Effect of Hydrogen Treatment in Titanium Ti-6Al-4V Alloy

2011 ◽  
Vol 183 ◽  
pp. 179-184 ◽  
Author(s):  
Maria Sozańska
Keyword(s):  
Titanium Alloy ◽  
High Temperature ◽  
Titanium Hydride ◽  
High Stress ◽  
Absorption Capacity ◽  
Hydrogen Gas ◽  
Hydrogen Treatment ◽  
Two Phase ◽  
Deformation Phase ◽  
Gas Atmosphere

Positive nature of the effects of hydrogen on the properties of titanium alloys is manifested in the high temperature hydrogen treatment (HTM - Hydrogen Treatment of Materials), where hydrogen is temporary alloying component. This is possible because of the high values ​​of diffusion coefficients can be easily introduced into the titanium and it just as easily removed. Titanium and its alloys exhibit a high affinity for hydrogen absorption capacity, about 60% at. hydrogen at 600 °C. The hydrogen in titanium alloy is present in the form – an interstitial solution or titanium hydride. Since the specific volume of titanium hydride is about 13 ÷ 17% higher compared to α phase, it is high stress in the crystal lattice of this phase leads to local plastic deformation and large deformation phase. The paper presents the results of the possibilities of hydrogen using as a temporary alloying element in Ti-6Al-4V alloy. Treatment of hydrogen alloy consisted of three stages: hydrogenation in hydrogen gas atmosphere at 650 °C, a cyclic hydrogen-treatment (3 cycles 650 °C or 950 °C to 250 °C) and a dehydrogenation in vacuum (550 °C). It was shown that hydrogen affects appreciably changes the microstructure of surface layer of the tested titanium alloy. The aim of this study is thus to determine the effect of hydrogen on the two-phase microstructure, hardness, and corrosion resistance of the titanium alloy Ti-6Al-4V due to high-temperature hydrogen treatment.

Benefits and Drawbacks of Hydrogen Effect in Microstructure on Titanium Ti-6Al-4V Alloy

2011 ◽  
Vol 176 ◽  
pp. 157-171 ◽  
Author(s):  
Maria Sozańska ◽  
Wojciech Szkliniarz
Keyword(s):  
Titanium Alloy ◽  
Titanium Alloys ◽  
Hydrogen Gas ◽  
Hydrogen Effect ◽  
Hydrogen Treatment ◽  
Surface Layers ◽  
Two Phase ◽  
Treatment Information ◽  
Gas Atmosphere ◽  
Cyclic Heat

We present herein the effects of hydrogen on the microstructure of surface layers of two-phase titanium Ti-6Al-4V alloy. We describe the damage caused by hydrogen and the possibilities of using hydrogen as a temporary alloying element. The paper regarding the HTM - Hydrogen Treatment of Materials as an attractive method for controlling microstructure and improving final mechanical properties of titanium alloys. Hydrogen treatment consists of three stages: hydrogenation in a hydrogen gas atmosphere (600 °C), cyclic heat hydrogen treatment (300 °C), and dehydrogenation in vacuum (550 °C). We present the possibilities of hydrogen treatment for controlling the microstructure layer of titanium alloy and show results for the corrosion resistance of Ti-6Al-4V titanium alloy after hydrogen treatment. Information about the hydrogen effect on titanium alloys, based on selected publications and the authors’ experience, is also presented.

Characterization of precipitates of Ti3Al in a titanium alloy

1996 ◽  
Vol 54 ◽  
pp. 1008-1009
Author(s):  
X.D. Zhang ◽  
J.M.K. Wiezorek ◽  
D.J. Evanst ◽  
H.L. Fraser
Keyword(s):  
Titanium Alloy ◽  
High Temperature ◽  
Aircraft Engine ◽  
Alpha Phase ◽  
Microstructural Stability ◽  
Beta Titanium Alloy ◽  
Two Phase ◽  
Beta Titanium ◽  
Alpha Beta

A two phase alpha-beta titanium alloy, Ti-6Al-2Mo-2Cr-2Sn-2Zr-0.2Si (Ti-6-22-22S), has recently been reconsidered as a high temperature material for aircraft engine applications. This alloy exhibits specific strength and fracture toughness superior to those of Ti-6A1-4V. However, similar to other alpha-beta titanium alloys, microstructural stability is one of the major concerns regarding industrial application of Ti-6-22-22S, since changes of the microstructure during long term high temperature exposure significantly affect the performance of components. Two types of precipitates have been observed in Ti-6-22-22S alloys, namely silicides and alpha 2-Ti3Al. The presence of intermetallic precipitates, such as alpha 2-Ti3Al, in the parent alpha matrix has been reported to result in brittle behaviour of the alpha-beta alloys due to the formation of intense planar slip bands. The present paper presents results of the characterization of intermetallic alpha2-Ti3Al precipitates in the alpha phase by methods of scanning and transmission electron microscopy (SEM and TEM respectively).

Positive Hydrogen Effect in Structure Surface Layers on Ti Alloy

2012 ◽  
Vol 186 ◽  
pp. 263-266 ◽  
Author(s):  
Maria Sozańska ◽  
Halina Garbacz
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloys ◽  
Temperature Treatment ◽  
Hydrogen Gas ◽  
High Temperature Treatment ◽  
Hydrogen Effect ◽  
Hydrogen Treatment ◽  
Surface Layers ◽  
Two Phase ◽  
Cyclic Heat

This paper presents the influence hydrogen effect in structure of surface layers on Ti-6Al-4V two-phase titanium alloys. It was described that hydrogen can be used as a temporary alloying element.The paper regarding the HTM - Hydrogen Treatment of Materials as an attractive method for controlling structure and improving final mechanical properties of titanium alloys. Hydrogen treatment consists of the three stages: hydrogenation in hydrogen gas atmosphere (600°C), cyclic heat hydrogen treatment (250°C), dehydrogenation in vacuum (550°C). This treatment uses purposeful, temporary introduction of hydrogen into the alloy to generate defects in its microstructure. Furthermore, it then causes recrystallization of defect microstructure during the dehydrogenation stage to grain refinement. This high-temperature treatment is very efficient for changing the microstructure and mechanical properties of two-phase titanium alloys.

Exsolution and inversion in pigeonite from the Whin Sill, Northern England

1978 ◽  
Vol 36 (1) ◽  
pp. 474-475
Author(s):  
P.P.K. Smith
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Homogeneous Nucleation ◽  
Silicate Mineral ◽  
Antiphase Boundaries ◽  
Two Phase ◽  
Primitive Form ◽  
The Core ◽  
Nucleation Mechanisms ◽  
And Inversion

Grains of pigeonite, a calcium-poor silicate mineral of the pyroxene group, from the Whin Sill dolerite have been ion-thinned and examined by TEM. The pigeonite is strongly zoned chemically from the composition Wo8En64FS28 in the core to Wo13En34FS53 at the rim. Two phase transformations have occurred during the cooling of this pigeonite:- exsolution of augite, a more calcic pyroxene, and inversion of the pigeonite from the high- temperature C face-centred form to the low-temperature primitive form, with the formation of antiphase boundaries (APB's). Different sequences of these exsolution and inversion reactions, together with different nucleation mechanisms of the augite, have created three distinct microstructures depending on the position in the grain.In the core of the grains small platelets of augite about 0.02μm thick have farmed parallel to the (001) plane (Fig. 1). These are thought to have exsolved by homogeneous nucleation. Subsequently the inversion of the pigeonite has led to the creation of APB's.

Heat Transfer Processes in High-Temperature Flows of Two-Phase Media

2001 ◽  
Vol 32 (7-8) ◽  
pp. 7
Author(s):  
M. I. Osipov ◽  
K. A. Gladoshchuk ◽  
A. N. Arbekov
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Two Phase ◽  
Transfer Processes
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