Mo Effect on the Microstructure in Co-Al-W-Based Superalloys

2010 ◽  
Vol 654-656 ◽  
pp. 420-423 ◽  
Author(s):  
Fei Xue ◽  
Zhi Qiang Li ◽  
Qiang Feng
Keyword(s):  
Solution Treatment ◽  
Aging Treatment ◽  
Eutectic Structure ◽  
Phase Precipitation ◽  
State Transformation ◽  
Solid State Transformation ◽  
Heat Treated ◽  
Cast Alloys ◽  
Do19 Phase ◽  
Mo Effect

The as-cast and heat-treated microstructure has been investigated in Co-Al-W-based superalloys with additions of 2 and 4 at.% Mo. The results revealed that Mo promoted the formation of (μ+γ) eutectic structure in the as-cast alloys and μ-phase precipitation after solution treatment. In addition, after aging treatment at 900oC, an extensive network of DO19 precipitates was observed, besides the γ+γ′ primary phases and the μ phase inherited from the as-cast and solution-treated conditions. Meanwhile, a solid-state transformation from the μ phase to the DO19 phase occurred; and long-term aging enhanced this transformation. In addition, high levels of Mo promoted the DO19-phase precipitation.

Microstructural Changes of FSX-414 Superalloy during TLP Bonding

2011 ◽  
Vol 312-315 ◽  
pp. 399-404 ◽  
Author(s):  
R. Bakhtiari ◽  
A. Ekrami
Keyword(s):  
Aging Treatment ◽  
Eutectic Structure ◽  
Isothermal Solidification ◽  
Heat Treatment Condition ◽  
Hardness Profile ◽  
Solution Treated ◽  
Tlp Bonding ◽  
Heat Treated ◽  
M23c6 Type ◽  
Bond Region

The as-cast FSX-414 Co-based superalloy samples were solution treated at 1150oC for 4h and then aged at 980oC for 4h. Specimens for joining were cut from the as-cast ingot and TLP bonding carried out at the same conditions as for the solution and solution+aging treatment, using MBF-30 interlayer. Microstructures were studied for as-cast, heat treated and TLP bonded specimens. These studies showed that the ununiform distributed carbides of MC type in the as-cast specimens replaced by M23C6 type carbides with uniform distribution in the heat treated microstructure. Due to complete isothermal solidification, no eutectic structure in the bond region were wasobserved, but some intermetallics in the diffusion affected zone (DAZ) were observed. Microhardness tests were used to compare the hardness of age hardened specimens with bonded specimens at the same heat treatment condition. Hardness profile also showed a peak in DAZ region in spite of complete isothermal solidification.

Effects of Non-Equilibrium Solidification and Aging Treatment on Microstructure Characteristic of a Ni-Base Superalloy

2014 ◽  
Vol 664 ◽  
pp. 3-7
Author(s):  
Da Fan Li ◽  
Xiao Hu ◽  
Wei Yang
Keyword(s):  
Volume Fraction ◽  
Dendritic Structure ◽  
Aging Treatment ◽  
Interface Energy ◽  
Transformation Process ◽  
Phase Changes ◽  
State Transformation ◽  
Solid State Transformation ◽  
Coarse Dendrite ◽  
Base Superalloy

Copper mould spray casting and aging treatment were performed to investigate the microstructure evolution of a Ni-base superalloy. With increasing the cooling rate during solidification, the morphology of primary γ phase changes from coarse dendrite to fine dendritic structure with radial-like feature, accompanied by the inhibition of γ′ phase due to the shortened period during the subsequent solid state transformation process. After aging treatment, both the size and volume fraction of γ′ phase are increased with prolonging the isothermal time, which generate the morphology transition of precipitates from irregular and spherical to ellipse and rectangle due to the competition between the interface energy and strain energy.

HREM of Rapidly Solidified Al-Li-Zr Based Alloys

1990 ◽  
Vol 48 (1) ◽  
pp. 54-55
Author(s):  
V. Radmilovic ◽  
G. Thomas ◽  
R. Kilaas ◽  
N. J. Kim
Keyword(s):  
Volume Fraction ◽  
Solution Treatment ◽  
Aging Treatment ◽  
High Resolution Electron Microscopy ◽  
Image Simulation ◽  
Large Volume Fraction ◽  
Heat Treated ◽  
Resolution Electron ◽  
Rapidly Solidified

During aging of Al-Li-Zr based alloys δ'(Al3Li) precipitates heterogeneously around β'(Al3Zr), forming so-called composite precipitate[l-4], that has important effects on the mechanical behavior of these alloys. As has been observed in several investigations, the addition of small amount of Zr results in a fairly large volume fraction of β' in the microstructure, and this suggests that there may be a partitioning of Li in the β'. In the present investigation, high resolution electron microscopy (HREM) and image simulation have been used to perform detailed characterization of the chemistry and structure of β' precipitate.The alloy Al-3Li-1Cu-0.5Mg-0.5Zr (wt.%) has been heat treated as follows: a) solution treatment at 550°C for 2 hours and water quenching, b) aging treatment at 150°C for 4 hours or at 200°C for 8 hours and c) 10% cold working followed by aging at 175°C for 64 hours. HREM images were taken on a JEOL ARM electron microscope operating at 400 and 800kV. Simulated HREM images of the composite δ'/β' precipitate were calculated using CEMPAS multislice program described by Kilaas[5].

Microstructure Formation in Cast β-Solidifying γ-Titanium Aluminide Alloys

2010 ◽  
Vol 638-642 ◽  
pp. 1394-1399 ◽  
Author(s):  
Michael Oehring ◽  
Fritz Appel ◽  
Jonathan H.D. Paul ◽  
Renat M. Imayev ◽  
V.M. Imayev ◽  
...  
Keyword(s):  
Titanium Aluminide ◽  
Microstructure Formation ◽  
State Transformation ◽  
Solid State Transformation ◽  
Alloying Effect ◽  
Microstructural Refinement ◽  
Nucleation Sites ◽  
Cast Alloys ◽  
Titanium Aluminide Alloys ◽  
Kinetics Of

In view of the development of improved TiAl cast alloys the potential of the  transformation and its dependence on the addition of several alloying elements has been investigated. It was found that microstructural refinement in  solidifying alloys can be attributed to the alloying effect on the kinetics of the  transformation. This also holds for grain refinement through Borides which apparently serve as nucleation sites for the  phase in the solid-state transformation.

scholarly journals Effect of Zr Addition and Aging Treatment on the Tensile Properties of Al-Si-Cu-Mg Cast Alloys

2020 ◽  
Author(s):  
Jacobo Hernandez-Sandoval ◽  
Mohamed H. Abdelaziz ◽  
Agnes M. Samue ◽  
Herbert W. Doty ◽  
Fawzy H. Samuel
Keyword(s):  
Yield Strength ◽  
Tensile Properties ◽  
Tensile Testing ◽  
Quality Index ◽  
Prolonged Exposure ◽  
Aging Treatment ◽  
Tensile Tests ◽  
Heat Treated ◽  
Cast Alloys ◽  
Noticeable Reduction

The present study focused on the tensile properties at ambient and high temperatures of alloy 354 without and with the addition of zirconium. Tensile tests were performed on alloy samples submitted to various aging treatments, with the aim of understanding the effects of the addition made on the tensile properties of the alloy. Zirconium reacts only with Ti, Si, and Al in the alloys examined to form the phases (Al,Si)2(Zr,Ti) and (Al,Si)3(Zr,Ti). Testing at 25°C reveals that the minimum and maximum quality index values, 259 and 459 MPa, are observed for the as-cast and solution heat-treated conditions, respectively. The yield strength shows a maximum of 345 MPa and a minimum of 80 MPa within the whole range of aging treatments applied. The ultimate tensile and yield strength values obtained at room temperature for T5-treated samples stabilized at 250°C for 200 h are comparable to those of T6-treated samples stabilized under the same conditions, and higher in the case of elevated-temperature (250°C) tensile testing. Coarsening of the strengthening precipitates following such prolonged exposure at 250°C led to noticeable reduction in the strength values, particularly the yield strength, and a remarkable increase in the ductility values.

Nonstoichiometry effects on microstructure in amorphous CdGeAs2

1989 ◽  
Vol 47 ◽  
pp. 442-443
Author(s):  
K.S. Hong ◽  
Y. Berta ◽  
R.F. Speyer
Keyword(s):  
Binary Phase Diagram ◽  
Fused Silica ◽  
Chalcopyrite Structure ◽  
State Transformation ◽  
Solid State Transformation ◽  
Germanium Content ◽  
Crystallization Sequence ◽  
Heat Treated ◽  
Sample Capsule ◽  
Carbon Coated

The mechanism of nucleation and growth in amorphous semiconducting CdGeAs2 has been demonstrated with the aid of thermal analysis, TEM, and XRD to be: 1) germanium precursor formation, 2) nonstoichiometric chalcopyrite structure crystal growth from the germanium precursor, and 3) solid state transformation of the precursor to the chalcopyrite structure. This crystallization sequence does not follow the pseudo-binary phase diagram which indicates that only in the case of germanium content in excess of stoichiometric CdGeAs2 should α solid solution form in equilibrium with chalcopyrite structured CdGeAs2 (see Fig. 1). To establish the extent of the germanium precursor nucleation mechanism, samples of deficient (CdGe0.8As2), stoichiometric, and excess (CdGe1.2As2) germanium content were prepared in the bulk amorphous form.Samples were fabricated by water-quenching the molten compound, vacuum sealed in carbon coated (by pyrolysis) fused silica tubes. The amorphous ampoules were broken out of the tubes, sliced to fit the hermetically sealing sample capsule for the differential scanning calorimeter (DSC) and heat treated at 0.5°C/min to various points along the exotherms. The partially devitrified samples were mechanically thinned and ion-milled using a liquid nitrogen cold stage, for examination in the TEM.

X-ray diffraction and microstructural studies in 2 : 17 type Sm–Co magnetic alloys containing Fe, Cu, and Zr

1999 ◽  
Vol 14 (6) ◽  
pp. 2430-2435 ◽  
Author(s):  
R. Gopalan ◽  
T. S. R. K. Sastry ◽  
A. K. Singh ◽  
V. Chandrasekaran
Keyword(s):  
Single Phase ◽  
Solution Treatment ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
Rhombohedral Crystal Structure ◽  
Cast Alloys ◽  
Rhombohedral Crystal ◽  
Co Alloys ◽  
Microstructural Studies

X-ray diffraction and microstructural studies were carried out on 2 : 17 type Sm–Co alloys containing Fe, Cu, and Zr (13–14 at.% Sm, 57–60 at.% Co, 20–22 at.% Fe, 4 at.% Cu, and 3 at.% Zr) in as-cast and heat-treated conditions. Microstructural studies revealed that the as-cast alloys contain three phases. It was observed that the samples subjected to sintering at 1463 K for 45 min followed by a solution treatment at 1448 K for 1 h resulted in nearly a single-phase, rhombohedral crystal structure (Th2Zn17-type). Subsequent isothermal aging at 1123 K and ramp-cooling to 673 K resulted in a mixture of Sm2Co17- and SmCo5-type phases with the former as major phase. It was also found that samples (Sm > 13 at.%) sintered at temperatures >1463 K showed incipient melting and multiphase formation.

Two-Step Aging Behaviour of Solution Treated A356 System Alloy

2018 ◽  
Vol 941 ◽  
pp. 1083-1087
Author(s):  
Masahiko Iijima ◽  
Tomoya Ozasa ◽  
Susumu Ikeno ◽  
Kenji Matsuda ◽  
Seiji Saikawa
Keyword(s):  
Solution Treatment ◽  
Aging Treatment ◽  
Hardness Measurement ◽  
Mg Alloy ◽  
Peak Hardness ◽  
System Alloy ◽  
Solution Treated ◽  
Heat Treated ◽  
Final Aging ◽  
Positive Effect

Al-7mass%Si-0.3mass%Mg alloy is widely applied to the automotive components, such as road wheel or suspension frame because of having higher ductility and corrosion resistance. Two-step aging behavior of solution treated Al-7mass%Si-0.3mass%Mg system alloy A356 cast into permanent mold and solution treated was investigated by micro-vickers hardness measurement, optical microscopy (OM) and transmission electron microscopy (TEM). The microstructure of as-cast state was consist of primary crystallized α-Al and secondary crystallized eutectic phases. Al-7mass%Si-0.3mass%Mg alloy after casting, the test specimens were heat treated for different pre-aging temperatures at 273K, 348K and 423K for various times after solution treatment at 813K for 36ks. After pre-aging treatment, the test specimens were heat treated for artificial aging at 523K for various times. The peak hardness increased almost the same value when the pre-aging temperature was 273K. On the other hands, positive effect of the final-aging was occurred after pre-aging at 348K and 423K with significantly increasing hardness in the under-aging region. The fine precipitates were observed in the specimen which was final aging at 523K after pre-aging at 348K and 423K.Such a positive effect is considered due to the influence of precipitated phase mainly such as clusters and /or G.P.zone.The present study aims to investigate the effect of pre-aged temperature on final-aged behavior in A356 system alloy.

scholarly journals Effect of Heat Treatment on Microstructure and Tensile Property of Ti-6Al-6V-2Sn Alloy

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 556
Author(s):  
Qirui Wang ◽  
Xiaofei Lei ◽  
Ming Hu ◽  
Xin Xu ◽  
Rui Yang ◽  
...  
Keyword(s):  
Aging Temperature ◽  
Volume Fraction ◽  
Solution Treatment ◽  
Aging Treatment ◽  
Martensite Phase ◽  
Solution Temperature ◽  
Orthorhombic Martensite ◽  
Heat Treated ◽  
Different Temperatures ◽  
Alloy Heat

The microstructure and tensile properties of Ti-6Al-6V-2Sn alloy heat-treated at different solution and aging temperatures has been systematically investigated. Specimens were solution-treated at 970 °C (above the β transus) and 920 °C (below the β transus), respectively, followed by water quenching. When the alloy is quenched from 970 °C, α’ (hcp) and α˝ (orthorhombic) martensite phases co-exist in the microstructure. When it is quenched from 920 °C, α´ martensite phase does not form, while equiaxial primary α (αp) phase and α˝ are found in the microstructure. The results also show that the strength of the alloy increases but the ductility deteriorates as the solution temperature becomes higher when the aging treatment is unchanged. This is because the volume fraction of equiaxial αp phase is lower but the volume fraction of the acicular secondary α (αs) phase is higher for higher solution temperature. When the alloy is aged at different temperatures after the solution treatment at 900 °C, the strength of the alloy decreases with the increase of aging temperature and the ductility shows the opposite trend as the size of the acicular αs becomes longer and its volume fraction is lower at higher aging temperature.

Deforming Capability of Heat-Treated and Modified Al-40Si Alloy

2011 ◽  
Vol 697-698 ◽  
pp. 479-482
Author(s):  
An Hui Cai ◽  
X.F. Tan ◽  
W.K. An ◽  
X.S. Li ◽  
J.J. Zeng ◽  
...  
Keyword(s):  
Solution Treatment ◽  
Aging Treatment ◽  
Optical Microscope ◽  
Deformation Degree ◽  
Critical Deformation ◽  
Primary Si ◽  
Heat Treated ◽  
Deformation Ratio

The Al-40Si alloy was modified by 0.5 wt% Sr addition and heat treated using the solution treatment and aging treatment. Its deforming capacity and hardness variance were investigated. The microstructures of the deformed samples were analyzed using optical microscope. The results show that the hardness increases with increasing of the deformation degree. When the deformation ratio exceeds 10.1 %, the hardness sharply increases. When the deformation ratio exceeds 20.4 %, the hardness maintains almost unchanged. In addition, although the cracks are not observed on the surface when the deformation ratio is less than 14.6 %, the primary Si phase is cracked. Thus the critical deformation ratio of the studied Al-40Si alloy is 10.1 %.

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