scholarly journals Influence of grain structure on the deformation mechanism in martensitic shear reversion-induced Fe-16Cr-10Ni model austenitic alloy with low interstitial content: Coarse-grained versus nano-grained/ultrafine-grained structure

2016 ◽  
Vol 661 ◽  
pp. 51-60 ◽  
Author(s):  
V.S.A. Challa ◽  
R.D.K. Misra ◽  
M.C. Somani ◽  
Z.D. Wang
Keyword(s):  
Deformation Mechanism ◽  
Grain Structure ◽  
Coarse Grained ◽  
Austenitic Alloy ◽  
Ultrafine Grained Structure ◽  
Interstitial Content ◽  
Ultrafine Grained

Grain Refinement and Deformation Behavior of Ultrafine Grained Pd and Pd-Ag Alloys Produced by HPT

2008 ◽  
Vol 584-586 ◽  
pp. 182-187
Author(s):  
Lilia Kurmanaeva ◽  
Yulia Ivanisenko ◽  
J. Markmann ◽  
Ruslan Valiev ◽  
Hans Jorg Fecht
Keyword(s):  
Mechanical Properties ◽  
Deformation Behavior ◽  
Materials Science ◽  
High Pressure Torsion ◽  
Uniform Elongation ◽  
Grain Structure ◽  
Coarse Grained ◽  
Ultrafine Grain ◽  
Ultrafine Grained ◽  
Ultrafine Grain Structure

Investigations of mechanical properties of nanocrystalline (nc) materials are still in interest of materials science, because they offer wide application as structural materials thanks to their outstanding mechanical properties. NC materials demonstrate superior hardness and strength as compared with their coarse grained counterparts, but very often they possess a limited ductility or show low uniform elongation due to poor strain hardening ability. Here, we present the results of investigation of the microstructure and mechanical properties of nc Pd and Pd-x%Ag (x=20, 60) alloys. The initially coarse grained Pd-x% Ag samples were processed by high pressure torsion, which resulted in formation of homogenous ultrafine grain structure. The increase of Ag contents led to the decrease of the resulted grain size and change in deformation behavior, because of decreasing of stacking fault energy (SFE). The samples with larger Ag contents demonstrated the higher values of hardness, yield stress and ultimate stress. Remarkably the uniform elongation had also increased with increase of strength.

Dynamics of friction processes on Al–Zn–Mg–Cu alloy with coarse-grained or ultrafine-grained structure

2018 ◽  
Author(s):  
O. A. Podgornyh ◽  
A. V. Filippov ◽  
S. Yu. Tarasov ◽  
N. N. Shamarin ◽  
E. O. Filippova
Keyword(s):  
Coarse Grained ◽  
Ultrafine Grained Structure ◽  
Cu Alloy ◽  
Ultrafine Grained

scholarly journals Hydrogen-induced failure of TiNi based alloy with coarse-grained and ultrafine-grained structure

2016 ◽  
Vol 2 ◽  
pp. 1481-1488 ◽  
Author(s):  
A. Baturin ◽  
A. Lotkov ◽  
V. Grishkov ◽  
I. Rodionov ◽  
K. Krukovskiy
Keyword(s):  
Coarse Grained ◽  
Ultrafine Grained Structure ◽  
Ultrafine Grained

High Strength Ti of Substantial Interstitial Contents Produced by Back Pressure Equal Channel Angular Consolidation of Dehydrided Particles

2008 ◽  
Vol 584-586 ◽  
pp. 92-96 ◽  
Author(s):  
Wei Xu ◽  
Xiao Lin Wu ◽  
D. Sadedin ◽  
Grant Wellwood ◽  
Kenong Xia
Keyword(s):  
Grain Boundaries ◽  
High Strength ◽  
Back Pressure ◽  
Grain Structure ◽  
Interstitial Content ◽  
Ultrafine Grains ◽  
Ultrafine Grained ◽  
The One ◽  
Ti Powder ◽  
Non Equilibrium

Back pressure equal channel angular (BP-ECA) processing was utilised to consolidate a dehydrided (DH) Ti powder of high interstitial content (1.15 wt.% O, 0.09 wt.% N) at 630°C into fully dense bulk ultrafine-grained (UFG) Ti. The consolidated samples showed an increase in the contents of oxygen (1.34 wt.%) and nitrogen (0.3 wt.%). The measured densities of 4.53 g/cm3 for the consolidated samples after 1 and 3 passes were very close to the theoretical value of pure Ti. TEM revealed the formation of a bimodal microstructure in the one-pass sample, comprising equiaxed grains of several micrometers in size with ultrafine grains of the order of 100 nm uniformly distributed at the triple grain junctions. Most grains had high-angle grain boundaries with some boundaries exhibiting non-equilibrium characteristics. Upon further BP-ECA processing to three passes, the micrometer-sized grains were refined down to the ultrafine level and copious nanoscale deformation twins were introduced by severe plastic strain into those ultrafine grains of the order of 100 nm. As a result of high interstitial contents and refined grains, the sample after processing for 3 passes exhibited remarkably enhanced true yield and ultimate strengths of 1510 and 2050 MPa, respectively. Significantly, a noticeable compressive ductility was simultaneously attained despite such a high interstitial content, thanks probably to the non-equilibrium grain boundaries, bimodal grain structure and the occurrence of deformation twinning.

scholarly journals The Effects of Chemical Etching and Ultra-Fine Grain Structure of Titanium on MG-63 Cells Response

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 510
Author(s):  
Denis Nazarov ◽  
Elena Zemtsova ◽  
Vladimir Smirnov ◽  
Ilya Mitrofanov ◽  
Maxim Maximov ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Chemical Etching ◽  
Grain Structure ◽  
Coarse Grained ◽  
Etching Time ◽  
Force Microscopy ◽  
Flight Mass Spectrometry ◽  
Fine Grain ◽  
Atomic Force ◽  
Ultrafine Grained

In this work, we study the influence of the surface properties of ultrafine grained (UFG) and coarse grained (CG) titanium on the morphology, viability, proliferation and differentiation of osteoblast-like MG-63 cells. Wet chemical etching in H2SO4/H2O2 and NH4OH/H2O2 solutions was used for producing surfaces with varying morphology, topography, composition and wettability. The topography and morphology have been studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The composition was determined by time of flight mass-spectrometry (TOF-SIMS) and X-ray photoelectron spectroscopy (XPS). The results showed that it is possible to obtain samples with different compositions, hydrophilicity, topography and nanoscale or/and microscale structures by changing the etching time and the type of etching solution. It was found that developed topography and morphology can improve spreading and proliferation rate of MG-63 cells. A significant advantage of the samples of the UFG series in comparison with CG in adhesion, proliferation at later stages of cultivation (7 days), higher alkaline phosphatase (ALP) activity and faster achievement of its maximum values was found. However, there is no clear benefit of the UFG series on osteopontin (OPN) expression. All studied samples showed no cytotoxicity towards MG-63 cells and promoted their osteogenic differentiation.

The Development of Superplasticity and Deformation Mechanism Maps in an Ultrafine-Grained Magnesium Alloy

2016 ◽  
Vol 879 ◽  
pp. 48-53
Author(s):  
Megumi Kawasaki ◽  
Roberto B. Figueiredo ◽  
Terence G. Langdon
Keyword(s):  
Deformation Mechanism ◽  
Elevated Temperatures ◽  
Grain Boundary Sliding ◽  
Grain Structure ◽  
Superplastic Behavior ◽  
Ultrafine Grained ◽  
Controlling Mechanism ◽  
Zk60 Alloy ◽  
Boundary Sliding ◽  
Coble Creep

Magnesium alloys with refined grain structure are often superplastic at elevated temperatures with maximum elongations up to more than 1000%. The superplastic behavior of this material agrees with deformation by grain boundary sliding. Dislocation climb becomes the rate controlling mechanism at higher stresses but the rate controlling mechanism at lower stresses is not fully documented. This report examines the development of superplasticity in a magnesium ZK60 alloy and shows that an increase in stress exponent and decrease in elongation takes place at low stresses. Deformation mechanism maps are constructed considering Regions I, II and III and Coble creep.

Description of the Superplastic Flow Process by Deformation Mechanism Maps in Ultrafine-Grained Materials

2016 ◽  
Vol 838-839 ◽  
pp. 51-58 ◽  
Author(s):  
Megumi Kawasaki ◽  
Terence G. Langdon
Keyword(s):  
Deformation Mechanism ◽  
Elevated Temperatures ◽  
High Pressure Torsion ◽  
Processing Technique ◽  
Superplastic Flow ◽  
Coarse Grained ◽  
Ultrafine Grain ◽  
Flow Process ◽  
Ultrafine Grained ◽  
Wide Range

The synthesis of ultrafine-grained (UFG) materials is very attractive because small grains lead to excellent creep properties including superplastic ductility at elevated temperatures. Severe plastic deformation (SPD) is an attractive processing technique for refining microstructures of metallic materials to have ultrafine grain sizes within the submicrometer to even the nanometer level. Among the SPD techniques, most effective processing is conducted through equal-channel angular pressing (ECAP) and high-pressure torsion (HPT) and there are numerous reports demonstrating the improved tensile properties at elevated temperature. This report demonstrates recent results on superplasticity in metals after ECAP and HPT. Moreover, superplastic flow of the UFG materials is evaluated by using flow mechanisms developed earlier for coarse-grained materials and depicted by plotting deformation mechanism maps which provide excellent visual representations of flow properties over a wide range of testing conditions.

Nanostructuring a Zr-Hf Alloy via Large Strain Rolling

2007 ◽  
Vol 539-543 ◽  
pp. 2843-2848 ◽  
Author(s):  
Maria Teresa Pérez-Prado ◽  
F. Salort ◽  
Ling Jiang ◽  
Oscar A. Ruano ◽  
M.E. Kassner
Keyword(s):  
Strain Rate ◽  
Deformation Mechanism ◽  
High Strain ◽  
Large Strain ◽  
Rolling Texture ◽  
Liquid Nitrogen Temperature ◽  
Coarse Grained ◽  
Dislocation Slip ◽  
Ultrafine Grained ◽  
Different Thickness

A coarse grained Zr-Hf alloy has been subjected to one rolling pass with different thickness reductions ranging from 10% to 80%. Rolling was performed at three temperatures: 300°C, room temperature (RT) and liquid nitrogen temperature (-196°C). It has been found that, with increasing strain per pass, i.e., with increasing strain rate, the deformation mechanism changes from twinning to dislocation slip. The minimum strain per pass necessary to trigger the transition in deformation mechanism decreases with decreasing temperature. High strain, high strain-rate deformation leads to the development of an ultrafine grained structure. Simultaneously, a basal type rolling texture forms. At the higher temperatures (RT and above) a recrystallization texture component is also present. Thus, nanostructuring of this Zr-Hf alloy during severe rolling is attributed to a combination of grain subdivision by the formation of geometrically necessary boundaries and to nucleation and growth phenomena taking place as a consequence of rapid adiabatic heating.

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