Hot Corrosion of Aluminide Coated Ti-Al-Cr-Nb-Zr-Y Intermetallic Alloys

2015 ◽  
Vol 1112 ◽  
pp. 363-366 ◽  
Author(s):  
Eddy Basuki ◽  
Fadhli Mohammad ◽  
Ahmad Fauzi ◽  
Djoko Prajitno
Keyword(s):  
Corrosion Rate ◽  
High Activity ◽  
High Temperatures ◽  
Corrosion Behavior ◽  
Hot Corrosion ◽  
Intermetallic Alloy ◽  
Experimental Results ◽  
Intermetallic Alloys ◽  
Two Phase ◽  
Aluminide Coatings

Pack aluminide coatings were performed on a Ti-Al-Cr-Nb alloy doped with zirconium and yttrium having two phase of a2-Ti3Al and g-TiAl microstructure. The high activity TiAl3-based coating was developed from aluminizing process carried out at 850°C for 25 hours in a pack containing 20%-wt Al, 2%wt NH4Cl, and 78%wt Al2O3. During applications at high temperatures, the coating can degrade due to the interaction between the coated system and the environment exhibit high corrosion potentials. This study investigates the hot corrosion behavior of high-activity aluminide coated Zr-Y doped a2-Ti3Al/g-TiAlCrNb intermetallic alloy at 700°C, 800°C, and 900°C in a mixture of 90% Na2SO4 and 10% NaCl. The experimental results showed that the addition of Zr and Y in the alloy reduces significantly the hot corrosion rate of the coating as resulted from the interdiffusion of these elements from the alloy to the coatings and influence the behavior of the TiAl3-based coatings.

Structure and hot corrosion behavior of platinum-modified aluminide coatings

1987 ◽  
Vol 32 (1-4) ◽  
pp. 111-126 ◽  
Author(s):  
R. Streiff ◽  
O. Cerclier ◽  
D.H. Boone
Keyword(s):  
Corrosion Behavior ◽  
Hot Corrosion ◽  
Aluminide Coatings

Effect of the Flow Velocity on the Corrosion Behavior of UNS S41426 Stainless Steel in the Extremely Aggressive Oilfield Environment for the Tarim Area

CORROSION ◽  
10.5006/2813 ◽  
2020 ◽  
Vol 76 (7) ◽  
pp. 654-665 ◽  
Author(s):  
Yang Zhao ◽  
Limin Chang ◽  
Tao Zhang ◽  
Junfeng Xie ◽  
Yan Chen ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Corrosion Rate ◽  
Phase Boundary ◽  
Flow Velocity ◽  
Passive Film ◽  
Corrosion Behavior ◽  
Pitting Corrosion ◽  
Defect Density ◽  
Electrochemical Techniques ◽  
Experimental Results

Effect of flow velocity on the passive film and pitting corrosion behavior of UNS S41426 stainless steel (SS) under the extreme oilfield environment was investigated using different techniques such as microscopy, nanoindentation, and electrochemical techniques. The experimental results show that the corrosion rate of UNS S41426 SS increased with velocity. The increase in flow velocity decreased the thickness and content of amorphous Cr(OH)3 (s) in the film. This in turn increased the density of phase boundary, resulting in a higher defect density. Thus, the UNS S41426 SS film became susceptible to breaking. Furthermore, the pitting had a higher susceptibility to grow to a larger size both in the vertical and horizontal directions with the increase in flow velocity.

Alloy design for reducing V content of dual two-phase Ni3Al-Ni3V intermetallic alloys

2012 ◽  
Vol 1516 ◽  
pp. 127-132
Author(s):  
Takahiro Hashimoto ◽  
Yasuyuki Kaneno ◽  
Takayuki Takasugi
Keyword(s):  
Electron Concentration ◽  
Valence Electron ◽  
Base Alloy ◽  
Intermetallic Alloy ◽  
Alloy Design ◽  
Valence Electron Concentration ◽  
Intermetallic Alloys ◽  
Two Phase ◽  
Phase Intermetallic

ABSTRACTThe objective of this study is to establish alloy designing which can reduce the amount of V for a Ni-base dual two-phase intermetallic alloy, without degenerating the dual two-phase microstructure. It was demonstrated that the favorable dual two-phase microstructure will be maintained as far as the valence electron concentration (e/a) of the alloys added by Cr is not so much different from that of the base alloy (i.e. the alloy without additive elements). Consequently, it was found that the dual two-phase microstructure was maintained even though the amounts of V were reduced by 7 at.%, 7 at.%, and 10at.% by substituting of Cr for V, Cr for both of Ni and V, and Cr for Ni, respectively. The hardness of the alloys with reduced V content was higher than that of the base alloy.

Effect of compositional modification on ductility of B2 phase in Ti–Al–Nb intermetallic alloy

2002 ◽  
Vol 17 (10) ◽  
pp. 2611-2614 ◽  
Author(s):  
Feng Tang ◽  
Masuo Hagiwara
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
Phase State ◽  
Intermetallic Alloy ◽  
Chemical Compositions ◽  
Intermetallic Alloys ◽  
Two Phase ◽  
Room Temperature Ductility ◽  
Single Phase State ◽  
B2 Phase

Room-temperature ductility of two Ti–Al–Nb intermetallic alloys with close chemical compositions was investigated by tensile testing. The two alloys' ductilities in the B2 single-phase state were significantly different, which indicated that the ductility of B2 phase state was sensitive to the chemical composition. The alloy with more ductile B2 phase exhibited higher ductility in O + B2 two-phase state.

Hot corrosion behavior of Pt-Ir modified aluminide coatings on the nickel-base single crystal superalloy TMS-82+

2007 ◽  
Vol 22 (1) ◽  
pp. 206-216 ◽  
Author(s):  
Y.N. Wu ◽  
A. Yamaguchi ◽  
H. Murakami ◽  
S. Kuroda
Keyword(s):  
Single Crystal ◽  
Corrosion Behavior ◽  
Hot Corrosion ◽  
Aluminide Coating ◽  
Mass Gain ◽  
Heating Time ◽  
Single Crystal Superalloy ◽  
Aluminide Coatings ◽  
Corrosion Kinetics ◽  
Nickel Base

Platinum-iridium films (Ir = 0, 32, 46, 83, 100 at.%) were deposited on the nickel-base single crystal superalloy through magnetron sputtering. After annealing and aluminizing, the Pt-Ir modified aluminide coatings mainly consisted of PtAl2 and β-(Ni,Pt,Ir)Al phases. Hot corrosion resistance of Pt-Ir modified aluminide coatings with the different Ir contents were evaluated by exposure at 1173 K in the presence of the 90%Na2SO4 + 10%NaCl (wt%) salt deposits. The corrosion kinetics curves of the specimens were plotted up to 100 h heating time. The phase constitution, morphology of corrosion products, and element concentrations along the cross section were also measured. The lowest mass gain (0.299 mg/cm2, after 100 h) was observed for Pt-46Ir aluminide coating because the dense and continuous protective Al2O3 scale formed. Phase transformation from β-(Ni,Pt)Al to γ′-(Ni,Pt)3Al, characteristics of the scale, and protection by Pt/Ir enriched layer had the important effects on the hot corrosion behavior of modified aluminide coatings.

Deformation Microstructures of Two-Phase Intermetallic Alloy Composed of Ni3Al and Ni3V in Single Crystalline Form

2012 ◽  
Vol 706-709 ◽  
pp. 1077-1082 ◽  
Author(s):  
T. Moronaga ◽  
Yasuyuki Kaneno ◽  
Hiroshi Tsuda ◽  
Takayuki Takasugi
Keyword(s):  
Room Temperature ◽  
Dislocation Motion ◽  
Intermetallic Alloy ◽  
High Flow ◽  
Crystalline Form ◽  
Intermetallic Alloys ◽  
Flow Strength ◽  
Two Phase ◽  
Transmission Electron ◽  
Phase Intermetallic

Two-phase single-crystal intermetallic alloys composed of Ni3Al (L12) and Ni3V (D022) with some orientations were compressed at various temperatures, and their deformation microstructures were observed by transmission electron microscopy (TEM). The deformation at room temperature was governed by the glide motion of dislocations in the primary Ni3Al precipitates and the activation of the microtwins in the Ni3V variant structures in the channel regions. The interfaces between the primary Ni3Al precipitates and the Ni3V variant structures are suggested to work as the barriers to the dislocation motion. While, at temperature above the peak temperature (873 K), the deformation microstructures of the two-phase intermetallic alloy exhibited the ribbon-like deformation microstructures penetrating the constituent phases i.e. through the interfaces between primary Ni3Al precipitates and the Ni3V variant structures in the channel regions. It was also suggested that the superior strength in the two-phase intermetallic alloys is due to the high flow strength of the Ni3V phases and to the interfacial hardening receiving when the dislocations activated in the primary Ni3Al precipitates propagate to the channel regions.

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