Microstructure and Mechanical Properties of Nanostructured Intermetallic Alloy Based on Ti2AlNb

2008 ◽  
Vol 584-586 ◽  
pp. 153-158
Author(s):  
M.R. Shagiev ◽  
G.A. Salishchev
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Room Temperature ◽  
Thermomechanical Processing ◽  
Nanocrystalline Structure ◽  
Nanostructured Material ◽  
Intermetallic Alloy ◽  
Superplastic Behavior ◽  
Average Grain Size ◽  
Rolling Temperatures

Homogeneous nanocrystalline structure with the average grain size of about 300 nm was produced in Ti2AlNb-based intermetallic alloy by a thermomechanical processing which included multistep isothermal forging at temperatures below the β-transus and intermediate annealings. Nanostructured material possessed excellent mechanical properties. At room temperature, elongations up to 25% were obtained and the ultimate strength reached 1400 MPa. The alloy exhibited superplastic behavior in the temperature range of 850-1000°C. The maximum elongation of 930% and steady state flow stress σ50 of about 125 MPa were obtained at 900°C and strain rate of 4.2×10-3 s-1. The rolling temperatures of nanostructured alloy were defined from analysis of its mechanical behavior at a typical rolling strain rate of about 10-1 s-1 and intermetallic sheets with improved mechanical properties were produced.

Improved Mechanical Properties of Ti2AlNb-Based Intermetallic Alloys and Composites

2008 ◽  
Vol 59 ◽  
pp. 105-108 ◽  
Author(s):  
M.R. Shagiev ◽  
R.M. Galeyev ◽  
Oleg R. Valiakhmetov ◽  
Rinat V. Safiullin
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Composite Plates ◽  
Nanostructured Material ◽  
Intermetallic Alloys ◽  
Steady State Flow ◽  
Superplastic Behavior ◽  
Homogeneous Microstructure ◽  
Average Grain Size

Mechanical properties of a Ti2AlNb-based intermetallic alloy both at room and elevated temperatures were considerably improved due to formation of a homogeneous microstructure with the average grain size of about 300 nm. At room temperature, elongations up to 25% were obtained and the ultimate strength reached 1400 MPa. The alloy exhibited superplastic behavior in the temperature range of 850-1000°C. The maximum elongation of 930% and steady state flow stress 50 of about 125 MPa were obtained at 900°C and strain rate of 4.210-3 s-1. The nanostructured material was used for production of intermetallic sheets and multilayer composite plates consisting of alternating layers of orthorhombic intermetallic and commercial high temperature titanium alloy. Ti2AlNb-based sheets and composites exhibited improved mechanical properties.

AEM Investigation of a Thermomechanically Processed U-6NB Alloy

1985 ◽  
Vol 43 ◽  
pp. 354-355
Author(s):  
Gail M. Ludtka
Keyword(s):  
Mechanical Properties ◽  
Solution Heat Treatment ◽  
Room Temperature ◽  
Thermomechanical Processing ◽  
High Yield ◽  
Ultrafine Grain ◽  
Superplastic Behavior ◽  
High Yield Strength ◽  
Ultrafine Grain Size ◽  
Before And After

The uranium-6 niobium (U-6Nb) alloy has been shown to exhibit elongations of 400-600% after a thermomechanical processing (TMP) sequence. This sequence (below the monotectoid temperature of 647°C) was utilized to develop the ultrafine grain size essential for superplastic behavior. The room temperature mechanical properties of the thermomechanically processed (TMP) U- 6Nb alloy before and after a gamma solution heat treatment (GSHT) were measured and compared to conventionally processed, GSHT U-6Nb alloy. These data are in Table I. The data show that the GSHT conditions have comparable mechanical properties and, so, the prior TMP treatment does not cause any loss of properties. However, the as-thermomechanically processed U-6Nb alloy exhibits negligible ductility and an extremely high yield strength. Metallography and AEM techniques have been utilized to characterize the TMP U- 6Nb microstructure to explain this behavior.

Effect of Small Addition of Si on Superplastic Elongation at Room Temperature in Zn-Al Eutectoid Superplastic Alloy

2014 ◽  
Vol 922 ◽  
pp. 328-331 ◽  
Author(s):  
Yuhei Kamiya ◽  
Masaki Ninomiya ◽  
Tokuteru Uesugi ◽  
Yorinobu Takigawa ◽  
Kenji Higashi
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Room Temperature ◽  
Tensile Tests ◽  
Al Alloy ◽  
Superplastic Behavior ◽  
Superplastic Alloy ◽  
Average Grain Size ◽  
Before And After ◽  
Si Content

Recent experimental data have revealed that a small amount of impurity can significantly influence the superplastic behavior in Zn-Al eutectoid superplastic alloy. However, the effect of Si content on the superplastic behavior in Zn-Al alloy has not been reported. In this study, the superplastic behavior at a room temperature of two grades of the Zn-Al eutectoid superplastic alloy was studied under identical conditions of grain size, temperature, and strain rate. These two grades were prepared from high-purity Zn, Al and Al-Si alloy using the same procedure but different Si impurity levels; Zn-Al-10Si and Zn-Al-1000Si contain 10 and 900 wt. ppm of Si, respectively. As a result of annealing treatments, an average grain size of 0.6 μm in both grades. To investigate the effects of Si content on superplastic properties, the tensile tests were performed at a room temperature of 298 K and a constant strain rate of 1×10-3 s-1. Microstructures before and after the tensile tests was observed using a scanning electron microscope. The experimental results show that the elongations decreased with increasing the Si content. In contrast, the flow stress of Zn-Al alloys was not affected by the Si content. On the microstructure observation of the two grades of the Zn-Al alloy before and after the tensile tests, cavities existed at grain boundaries and strain enhanced grain growth was observed.

EVOLUTION OF MICROSTRUCTURE AND MECHANICAL PROPERTIES OF THE Ni-25Al-27.5Fe-1.0Nb INTERMETALLIC ALLOY AFTER THERMAL MECHANICAL TREATMENT

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1053-1059
Author(s):  
CHIH-CHIANG FU ◽  
JASON SHIAN-CHING JANG ◽  
HAN-CHANG TSAI ◽  
TSUNG-HSIUNG LI
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Mechanical Treatment ◽  
Room Temperature ◽  
Cast Alloy ◽  
High Strength ◽  
Intermetallic Alloy ◽  
Dendritic Microstructure ◽  
Microstructure And Mechanical Properties ◽  
Evolution Of Microstructure

The evolution of microstructure and mechanical properties of the Ni -25 Al -27.5 Fe -1.0 Nb intermetallic alloy after thermal mechanical treatment (TMT) was systematically investigated by means of X-ray diffractometry (XRD), scanning electron microscopy (SEM) with electron dispersive spectrum (EDS) capability, and atmosphere-controlled tensile test at room temperature with different strain rate. The results of XRD reveals that a matrix of β' phase [( Ni , Fe ) Al type ordered bcc structure] and a precipitated γ phase ( Ni 3 Fe fcc solid solution) co-exist in this alloy after TMT. The dendritic microstructure of the as-cast alloy was eliminated after TMT process. In parallel, a refined and homogeneous distributed lath precipitates can be obtained after annealing at 820 for 4 hr. Additionally, this alloy presents a relative high strength as well as ductile mechanical behavior (UTS~1320 MPa and ε~8%, respectively) at room temperature in air. A 30% improvement in yield strength is suggested to be contributed by the refined microstructure from the TMT. Moreover, the tensile strength and ductility of this alloy exhibit insensitive response with respect to the loading strain rate at room temperature.

Local Investigations of the Mechanical Properties of Ultrafine Grained Metals by Nanoindentations

2006 ◽  
Vol 503-504 ◽  
pp. 31-36 ◽  
Author(s):  
Johannes Mueller ◽  
Karsten Durst ◽  
Dorothea Amberger ◽  
Matthias Göken
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Room Temperature ◽  
Rate Sensitivity ◽  
Strain Rates ◽  
Fcc Metals ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Indentation Strain

The mechanical properties of ultrafine-grained metals processed by equal channel angular pressing is investigated by nanoindentations in comparison with measurements on nanocrystalline nickel with a grain size between 20 and 400 nm produced by pulsed electrodeposition. Besides hardness and Young’s modulus measurements, the nanoindentation method allows also controlled experiments on the strain rate sensitivity, which are discussed in detail in this paper. Nanoindentation measurements can be performed at indentation strain rates between 10-3 s-1 and 0.1 s-1. Nanocrystalline and ultrafine-grained fcc metals as Al and Ni show a significant strain rate sensitivity at room temperature in comparison with conventional grain sized materials. In ultrafine-grained bcc Fe the strain rate sensitivity does not change significantly after severe plastic deformation. Inelastic effects are found during repeated unloading-loading experiments in nanoindentations.

Superplastic Behavior of a Cu-Cr-Zr Alloy Subjected to ECAP

2016 ◽  
Vol 838-839 ◽  
pp. 404-409
Author(s):  
Roman Mishnev ◽  
Iaroslava Shakhova ◽  
Andrey Belyakov ◽  
Rustam Kaibyshev
Keyword(s):  
Grain Size ◽  
Dislocation Density ◽  
Strain Rate ◽  
Temperature Interval ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Superplastic Behavior ◽  
Average Grain Size ◽  
Gauge Section ◽  
Zr Alloy

A Cu-0.87%Cr-0.06%Zr alloy was subjected to equal channel angular pressing (ECAP) at a temperature of 400 °C up to a total strain of ~ 12. This processing produced ultra-fine grained (UFG) structure with an average grain size of 0.6 μm and an average dislocation density of ~4×1014 m-2. Tensile tests were carried out in the temperature interval 450 – 650 °C at strain rates ranging from 2.8´10-4 to 0.55 s-1. The alloy exhibits superplastic behavior in the temperature interval 550 – 600 °C at strain rate over 5.5´10-3 s-1. The highest elongation-to-failure of ~300% was obtained at a temperature of 575 °C and a strain rate of 2.8´10-3 s-1 with the corresponding strain rate sensitivity of 0.32. It was shown the superplastic flow at the optimum conditions leads to limited grain growth in the gauge section. The grain size increases from 0.6 μm to 0.87 μm after testing, while dislocation density decreases insignificantly to ~1014 m-2.

scholarly journals Molecular Dynamics Simulation Study of the Mechanical Properties of Nanocrystalline Body-Centered Cubic Iron

Surfaces ◽  
2020 ◽  
Vol 3 (3) ◽  
pp. 381-391
Author(s):  
Jan Herman ◽  
Marko Govednik ◽  
Sandeep P. Patil ◽  
Bernd Markert
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Strain Rate ◽  
Tensile Tests ◽  
Dynamics Simulation ◽  
Uniaxial Tensile ◽  
Body Centered Cubic ◽  
Bcc Iron ◽  
Average Grain Size ◽  
Study Results

In the present work, the mechanical properties of nanocrystalline body-centered cubic (BCC) iron with an average grain size of 10 Å were investigated using molecular dynamics (MD) simulations. The structure has one layer of crystal grains, which means such a model could represent a structure with directional crystallization. A series of uniaxial tensile tests with different strain rates and temperatures was performed until the full rupture of the model. Moreover, tensile tests of the models with a void at the center and shear tests were carried out. In the tensile test simulations, peak stress and average values of flow stress increase with strain rate. However, the strain rate does not affect the elasticity modulus. Due to the presence of void, stress concentrations in structure have been observed, which leads to dislocation pile-up and grain boundary slips at lower strains. Furthermore, the model with the void reaches lower values of peak stresses as well as stress overshoot compared to the no void model. The study results provide a better understanding of the mechanical response of nanocrystalline BCC iron under various loadings.

Effects of Temperature and Strain Rate on Compressive Mechanical Properties of Ultrafine-Grained CP Titanium

2007 ◽  
Vol 26-28 ◽  
pp. 381-384 ◽  
Author(s):  
Zhi Guo Fan ◽  
Chao Ying Xie
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Ultimate Strength ◽  
Room Temperature ◽  
Equal Channel Angular Extrusion ◽  
Coarse Grain ◽  
Ultrafine Grained ◽  
Effects Of Temperature ◽  
Cp Ti ◽  
Compressive Tests

Ultrafine-grained (UFG) CP Ti were successfully prepared by Equal Channel Angular Extrusion (ECAE) at 390°C~400°C, small than 0.5 um in size. The compressive tests for coarse grain (CG) and UFG Ti were carried out at room temperature (RT) and 77K. UFG Ti showed excellent ductility and higher strength than CG Ti at RT and 77 K. The strain hardening of UFG Ti was improved at 77 K. The compressive ultimate strengths of CG Ti and UFG Ti were both enhanced as the strain rate increased, but CG Ti showed more obvious temperature and strain rate dependence of flow stress, comparing with UFG Ti. When the strain rate increased to 1×10-1/s, the compressive ultimate strength of UFG Ti was kept almost constant, while the ultimate strength of CG Ti increased to the strength level of UFG Ti.

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