An Experimental and Modeling Investigation of Tensile Creep Resistance in a Stable Nanocrystalline Alloy

2020 ◽  
Author(s):  
C. Kale ◽  
S. Srinivasan ◽  
B.C. Hornbuckle ◽  
R.K. Koju ◽  
K. Darling ◽  
...  
Keyword(s):  
Creep Resistance ◽  
Nanocrystalline Alloy ◽  
Tensile Creep

An experimental and modeling investigation of tensile creep resistance of a stable nanocrystalline alloy

2020 ◽  
Vol 199 ◽  
pp. 141-154
Author(s):  
C. Kale ◽  
S. Srinivasan ◽  
B.C. Hornbuckle ◽  
R.K. Koju ◽  
K. Darling ◽  
...  
Keyword(s):  
Creep Resistance ◽  
Nanocrystalline Alloy ◽  
Tensile Creep

Microstructure and Creep Properties of AJ62 and AE44 Die-Casting Magnesium Alloys

2010 ◽  
Vol 638-642 ◽  
pp. 1546-1551 ◽  
Author(s):  
Andrzej Kiełbus ◽  
Tomasz Rzychoń
Keyword(s):  
Magnesium Alloys ◽  
Creep Resistance ◽  
Cell Structure ◽  
Creep Behaviour ◽  
Die Casting ◽  
Tensile Creep ◽  
Creep Properties ◽  
Die Cast ◽  
Subgrain Formation ◽  
Good Creep Resistance

Microstructure and tensile creep behaviour of the die-cast AE44 and AJ62 magnesium alloys has been studied at temperatures between 175°C and 200°C and at stresses in the range from 60 to 75 MPa. At the 175°C the AJ62 and AE44 alloys exhibit good creep resistance after 120h creep deformation. At 200°C the AE44 alloy shows still good creep resistance, whereas in the case of AJ62 alloy the rapid decreasing of creep resistance has been observed. TEM observations reveal dislocations cell structure in AE44 alloy after creep test. In AJ62 alloy subgrain formation and decreasing the dislocation density have been observed.

Mg-Zn-Y Alloys with Long-Period Stacking Ordered Phases: Deformation, Creep, Solute Segregation and Strengthening Mechanisms at Elevated Temperatures

2016 ◽  
Vol 879 ◽  
pp. 2204-2209 ◽  
Author(s):  
Zhi Qing Yang ◽  
Wei Wei Hu ◽  
Heng Qiang Ye
Keyword(s):  
Plastic Deformation ◽  
Creep Resistance ◽  
Basal Slip ◽  
Elevated Temperatures ◽  
Stacking Faults ◽  
Dislocation Motion ◽  
Tensile Creep ◽  
Lpso Phase ◽  
Long Period ◽  
Cottrell Atmospheres

Mg-Zn-Y alloys with long-period stacking ordered (LPSO) phases have superior strength at elevated temperatures. We studied plastic deformation and creep behavior of a Mg97Zn1Y2 (at.%) alloy. Deformation kinking of the LPSO phase plays an important role in strengthening the alloy during compression at elevated temperatures. Growth stacking faults with Zn/Y segregation can act as obstacles to non-basal slip and deformation twinning in Mg matrix. The tensile creep strain was only about 0.01% under a tensile stress of 70MPa for 100h at 200 °C, demonstrating excellent creep resistance of this alloy. Generation and motion of basal dislocations led to bending of LPSO phase during tensile creep of the Mg97Zn1Y2 (at.%) alloy. Plastic deformation in Mg grains was mostly achieved through basal slip during creep at temperatures below 200 °C, while non-basal slip through the generation and motion of “a + c” dislocations was activated with increasing the temperature to 200 °C and above. Dissociation of dislocations and Suzuki segregation on basal planes occurred widely in Mg matrix, which hindered dislocation motion and thus played an important role in preventing Mg grains from softening during deformation at elevated temperatures. In addition, Cottrell atmospheres were observed along dislocations in plastically deformed LPSO phase, impeding motion of dislocations. The superior strength and creep resistance of the Mg97Zn1Y2 (at.%) alloy at elevated temperatures are thus associated with the LPSO phase, stacking faults in Mg grains, formation of Cottrell atmospheres in LPSO and occurrence of Suzuki segregation in Mg.

Effect of TiO2 nanoparticles on the viscoelastic and time-dependent behaviors of TiO2/epoxy particulate nanocomposite

2017 ◽  
Vol 37 (2) ◽  
pp. 185-196 ◽  
Author(s):  
Hamid Reza Salehi ◽  
Manouchehr Salehi
Keyword(s):  
Epoxy Resin ◽  
Storage Modulus ◽  
Creep Resistance ◽  
Epoxy Resins ◽  
Loss Modulus ◽  
Tensile Creep ◽  
Titania Nanoparticles ◽  
Test Machine ◽  
Creep Tests ◽  
Mechanical Creep

Abstract In this work, the effects of nano titania are investigated on mechanical, creep, and viscoelastic behaviors of epoxy resin. For this purpose, 0.25, 0.5, and 1 vol.% of TiO2 nanoparticles were mixed with thermoset epoxy resin by mechanical and ultrasonic homogenizers and then the tensile, creep, and DMTA test samples were fabricated. The results of tensile tests show that the addition of TiO2 nanopowder slightly increased the strength and Young’s modulus of epoxy resin. However, the ultimate tensile strain or the rupture strain of nanocomposites is decreased. In addition, to understand the viscoelastic behavior of nanocomposites, the DMTA and tensile creep tests have been done. Tensile creep test has been done by DMTA and universal test machine. Both results confirmed that the creep resistance of nanocomposites has extensively improved by adding the titania nanoparticles. Variations of storage modulus, loss modulus, and tan (δ) by adding TiO2 nanopowder were examined in two modes of bending and tension. Storage and loss moduli of nanocomposite are considerably increased in all the states, but the storage modulus was more sensitive to TiO2 loading intensity. Thus, test results showed that introduction of TiO2 in the epoxy resin leads to the improvement of mechanical, creep resistance, and viscoelastic properties of nanocomposites. Due to the wide applications of epoxy resins in engineering devices, this method of reinforcement can be practical and useful to overcome some limitations of epoxy resins.

Tensile Creep Behaviors of a P-Type Structure Single Crystal Nickel-Base Superalloy

2007 ◽  
Vol 546-549 ◽  
pp. 1345-1348
Author(s):  
Hong Qiang Du ◽  
Su Gui Tian ◽  
Xing Fu Yu ◽  
Ming Gang Wang ◽  
Fan Lai Meng
Keyword(s):  
Microstructure Evolution ◽  
Creep Resistance ◽  
Type Structure ◽  
Tensile Creep ◽  
Stress Axis ◽  
Nickel Base Superalloy ◽  
Experimental Conditions ◽  
Direction Parallel ◽  
Microstructure Observation ◽  
P Type

By means of pre-compressive stress treated, the cubic γ΄ phase in alloy is transformed into the P-type structure along the direction parallel to the applied stress axis. The influence of the P-type structure on the creep lifetimes of alloy has been investigated by means of the tensile creep testing and microstructure observation. Results show that, compared with the A structure alloy, the P-type γ′ rafted alloy displays a shorter creep lifetimes under the experimental conditions. The microstructure evolution of the P-type structure alloy occurs during tensile creep, in which the p-type γ′ rafted phase is transformed into the N-type structure. The microstructure evolution alloy reduces the creep resistance of the alloy, this is one of the main reasons for reducing the creep resistance of the one.

Characterization of the Microstructure, Tensile and Creep Behavior of Powder Metallurgy Processed and Rolled Ti-6Al-4V-1B Alloy

2010 ◽  
Vol 436 ◽  
pp. 195-203 ◽  
Author(s):  
Wei Chen ◽  
Carl J. Boehlert
Keyword(s):  
Elevated Temperature ◽  
Powder Metallurgy ◽  
Creep Behavior ◽  
Creep Deformation ◽  
Deformation Behavior ◽  
Creep Resistance ◽  
Tensile Creep ◽  
Duplex Microstructure ◽  
Α Phase

This work investigated the microstructure and elevated-temperature (400-475oC) tensile and tensile-creep deformation behavior of a powder metallurgy (PM) rolled Ti-6Al-4V-1B(wt.%) alloy. The PM rolled Ti-6Al-4V-1B alloy exhibited a duplex microstructure, and it did not exhibit a strong α-phase texture compared with the PM extruded Ti-6Al-4V-1B alloy. The PM rolled Ti-6Al-4V-1B alloy exhibited greater creep resistance than the PM extruded Ti-6Al-4V-1B alloy as well as the as-cast Ti-6Al-4V-1B alloy.

The Creep Behaviors of Two Fine-grained XD TiAl Alloys Produced by Similar Heat Treatments

2004 ◽  
Vol 842 ◽  
Author(s):  
Hanliang Zhu ◽  
Dongyi Seo ◽  
Kouichi Maruyama ◽  
Peter Au
Keyword(s):  
Grain Boundaries ◽  
Creep Resistance ◽  
Lamellar Spacing ◽  
Heat Treatments ◽  
Tensile Creep ◽  
Microstructural Stability ◽  
Creep Tests ◽  
Tial Alloys ◽  
Fine Grained ◽  
Interlocked Grain

ABSTRACTThe microstructural characteristics and creep behavior of two fine-grained XD TiAl alloys, Ti-45Al and 47Al–2Nb–2Mn+0.8vol%TiB2 (at%), were investigated. A nearly lamellar structure (NL) and two kinds of fully lamellar (FL) structures in both alloys were prepared by selected heat treatments. The results of microstructural examination and tensile creep tests indicate that the 45XD alloy with a NL structure possesses an inferior creep resistance due to its coarse lamellar spacing and larger amount of equiaxed γ grains at the grain boundaries, whereas the same alloy in a FL condition with fine lamellar spacing lowers the minimum creep rates. Contrary to 45XD, the 47XD alloy with a NL structure exhibits the best creep resistance. However, 47XD with a FL structure with finer lamellar spacing shows inferior creep resistance. On the basis of microstructural deformation characteristics, it is suggested that the well-interlocked grain boundary and relatively coarse colony size in FL and NL 47XD inhibit sliding and microstructural degradation at the grain boundaries during creep deformation, resulting in better creep resistance. Therefore, good microstructural stability is essential for improving the creep resistance of these alloys.

Effect of Fiber Volume Fraction on High Temperature Creep of Al2O3-SiO2(sf)/AZ91D Composite

2011 ◽  
Vol 474-476 ◽  
pp. 548-552
Author(s):  
Jun Tian
Keyword(s):  
Creep Resistance ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Matrix Alloy ◽  
Short Fiber ◽  
Tensile Creep ◽  
Short Fibers ◽  
Creep Tests ◽  
Fiber Volume ◽  
The Matrix

Constant stress tensile creep tests were conducted on AZ91D–20 vol.%, 25 vol.%, and 30 vol.% Al2O3-SiO2short fiber composites and on an unreinforced AZ91D matrix alloy. The creep resistance of the reinforced materials is shown to be considerably improved compared with the matrix alloy. With the increasing volume fraction of short fibers, the creep resistance of AZ91D composites is improved, and their creep threshold stresses are also increased accordingly. Because of the increasing volume fraction of short fibers, loads of bearing and transmission of short fibers will increase, and thus the creep resistance of AZ91D composites further improves, but the precipitation of β-Mg17Al12precipitate increases in the number, it is easy to soften coarse, so that threshold stress of AZ91D composite does not increase greatly.

Improved creep resistance in anisotropic silicon nitride

2001 ◽  
Vol 16 (8) ◽  
pp. 2182-2185 ◽  
Author(s):  
Naoki Kondo ◽  
Yoshikazu Suzuki ◽  
Manuel E. Brito ◽  
Tatsuki Ohji
Keyword(s):  
Silicon Nitride ◽  
Creep Rate ◽  
Tensile Stress ◽  
Creep Behavior ◽  
Creep Resistance ◽  
Elevated Temperatures ◽  
Tensile Creep ◽  
Grain Alignment ◽  
Remarkable Improvement ◽  
Order Of Magnitude

Tensile creep behavior of silicon nitride with aligned rodlike grains (anisotropic silicon nitride), fabricated by superplastic forging, was investigated at elevated temperatures. Creep rate of the anisotropic silicon nitride was about 1 order of magnitude lower than that of the isotropic one (without forging). The stress sensitivities for the isotropic and anisotropic specimens at 1200 °C were 2.1 and 2.6, respectively, and that for the anisotropic specimen at 1250 °C was 3.6. The grain alignment should cause a remarkable improvement in the creep resistance when a tensile stress is applied along the alignment direction.

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