Structure and Properties of NiTi Shape Memory Alloys after Severe Plastic Deformation

2013 ◽  
Vol 738-739 ◽  
pp. 501-505 ◽  
Author(s):  
Danuta Stróż ◽  
Jakub Palka ◽  
Zdzisław Lekston ◽  
Grzegorz Dercz
Keyword(s):  
Plastic Deformation ◽  
Parent Phase ◽  
Nanocrystalline Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Multi Stage ◽  
Rich Alloy ◽  
Polygonized Structure ◽  
Niti Shape Memory Alloys ◽  
Maximal Strain

The results presented here concern two NiTi alloys (near-equiatomic NiTi and Ni-rich alloy) subjected to plastic deformation by compression combined with reversion oscillating torsion. The maximal strain obtained was εc = 6.20. Finally the alloys were annealed at the temperature range 300 – 500°C for 1 hour. The structure of the as-prepared alloys was studied with the use of temperature X-ray diffraction and TEM observations. Also the DSC and bend and free recovery ASTM tests were carried out. It was found that the structure consists of a mixture of highly deformed B2 parent phase and B19’ martensite. The TEM studies revealed some amorphous areas in the most strained region of the samples. Annealing at lower temperatures caused formation of nanocrystalline structure that grew to the microcrystalline and finally well-defined polygonized structure in annealed at 500°C specimens. Multi-stage transformation was observed in the annealed at lower temperatures samples.

Studies of NiTi Shape Memory Alloy after Severe Plastic Deformation

2010 ◽  
Vol 163 ◽  
pp. 137-140 ◽  
Author(s):  
Danuta Stróż ◽  
Grzegorz Dercz ◽  
Jacek Pawlicki ◽  
J. Palka
Keyword(s):  
Plastic Deformation ◽  
Shape Memory Alloy ◽  
Severe Plastic Deformation ◽  
Strain Distribution ◽  
Niti Alloy ◽  
Parent Phase ◽  
Niti Shape Memory Alloy ◽  
Compression Rate ◽  
X Ray ◽  
Maximal Strain

The results presented here concern the NiTi alloy subjected to plastic deformation by compression combined with reversion oscillating torsion. The compression rate was 0.05 mm/s and the torsion frequency and angle were 1Hz and ± 3o, respectively. The maximal strain obtained was c = 6.20. The structure of the deformed samples was studied with the use of X-ray phase analysis and TEM observations. It was found that the structure consists of a mixture of highly deformed B2 parent phase and B19’ martensite. The strain distribution after the applied plastic deformation was not uniform, the highest strain region was in the middle of the cylinder sample. In these regions small amount of the Ni2Ti phase was indentified. The TEM studies revealed some amorphous areas in the most strained region of the samples.

Influence of Severe Plastic Deformation on Physicomechanical Properties of Ti-40 mas % Nb Alloy

2016 ◽  
Vol 685 ◽  
pp. 525-529
Author(s):  
Zhanna G. Kovalevskaya ◽  
Margarita A. Khimich ◽  
Andrey V. Belyakov ◽  
Ivan A. Shulepov
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Cold Working ◽  
Young Modulus ◽  
Physicomechanical Properties ◽  
X Ray Diffraction ◽  
Refined Grains ◽  
X Ray ◽  
Initial Alloy ◽  
Composition Structure

The changes of the phase composition, structure and physicomechanical properties of Ti‑40 mas % Nb after severe plastic deformation are investigated in this paper. By the methods of microstructural, X-ray diffraction analysis and scanning electron microscopy it is determined that phase and structural transformations occur simultaneously in the alloy after severe plastic deformation. The martensitic structure formed after tempering disappears. The inverse α'' → β transformation occurs. The structure consisting of oriented refined grains is formed. The alloy is hardened due to the cold working. The Young modulus is equal to 79 GPa and it is less than that of initial alloy and close to the value obtained after tempering. It is possible that Young modulus is reduced by additional annealing.

Texture Development in a Model Al-Li Alloy Subjected to Severe Plastic Deformation

2006 ◽  
Vol 114 ◽  
pp. 337-344 ◽  
Author(s):  
Bogusława Adamczyk-Cieślak ◽  
Jaroslaw Mizera ◽  
Krzysztof Jan Kurzydlowski
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Equal Channel Angular Extrusion ◽  
Orientation Distribution ◽  
X Ray Diffraction ◽  
Technological Parameters ◽  
Initial State ◽  
Texture Characteristic ◽  
X Ray ◽  
Ultrafine Grained

The texture of Al – 0.7 wt. % Li alloy processed by two different methods of severe plastic deformation (SPD) has been investigated by X-ray diffraction, and analyzed in terms of the orientation distribution function (ODF). It was found that severe plastic deformation by both Equal Channel Angular extrusion (ECAE) and Hydrostatic Extrusion (HE) resulted in an ultrafine grained structure in an Al – 0.7 wt. % Li alloy. The microstructure, grain shape and size, of materials produced by SPD strongly depend on the technological parameters and methods applied. The texture of the investigated alloy differed because of the different modes of deformation. In the initial state the alloy exhibited a very strong texture consisting of {111} fibre component. A similar fibrous texture characteristic was also found after HE whereas after the ECAE the initial texture was completely changed.

Influence of Aging Treatments on the Structural and Mechanical Properties of AGS Alloy Wire Cold Drawn

2018 ◽  
Vol 18 ◽  
pp. 73-78
Author(s):  
Mokhtar Bayarassou ◽  
Mosbah Zidani ◽  
Hichem Farh
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Electron Microscope ◽  
Artificial Ageing ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
Alloy Wire ◽  
X Ray ◽  
Plastic Deformation Rate ◽  
Scanning Electron

The scope of this work is to study of microstructural changes and mechanical properties during natural and artificial ageing treatment of AGS Alloy wire cold drawn with different deformation at ENICAB in Biskra. And as well to know the phase formation during different deformation of aluminum alloys wires. as well as the combined influence of the plastic deformation rate and the aging temperature. Wire section reduction shows a change in microstructure and texture. The methods of characterization used in this work are: scanning electron microscope and X-ray diffraction, micro hardness (Hv).

Effect of Milling Speed on Properties of Fe-NbC Composite Prepared by Mechanical Alloying

2011 ◽  
Vol 471-472 ◽  
pp. 804-808 ◽  
Author(s):  
Siti Zalifah Md Rasib ◽  
Zuhailawati Hussain
Keyword(s):  
Mechanical Alloying ◽  
Mechanical Alloy ◽  
Metal Matrix ◽  
Nanocrystalline Structure ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Composite Fabrication ◽  
Milling Duration ◽  
Pellet Form

Nowadays, mechanical alloy (MA) method has turned up as one of a new and applicable method for metal matrix composite fabrication due to some advantages such as the ability to form nanocrystalline structure with improved properties. In this work, different milling speed of MA process (100, 200, 300 and 400 rpm) was performed on Fe-17.21wt%Nb-2.23wt%C with milling duration of 10 hours. The mixture was pressed and sintered at 1300oC into a pellet form. Investigation by X-ray diffraction, measurement of hardness and density were carried out. High milling speed resulted on crystalline-to-amorphous transition of XRD peaks of Fe and NbC phases. Different level of MA at different speed also produced fine NbC particles and strain hardening which resulted in increase value of hardness. The presence of pores, particularly in the composite with high milling speed, decreased the density of Fe-NbC composite.

New Preparation for Amorphous/Nanocrystalline Ni-Mo Alloys by Electrodeposition

2013 ◽  
Vol 702 ◽  
pp. 191-196 ◽  
Author(s):  
Ning Li ◽  
Lin Lin Wang ◽  
Xiao Ming Wang ◽  
Wei Zeng Chen
Keyword(s):  
Nickel Sulfate ◽  
Nanocrystalline Structure ◽  
Sulfate Solution ◽  
Carbonate Solution ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
X Ray ◽  
Nickel Carbonate ◽  
The Stability ◽  
Better Than

The amorphous/nanocrystalline Ni-Mo alloys are obtained in alkaline nickel carbonate solution in this paper. By using X-ray diffraction (XRD) and scanning electronic microscopy (SEM) to testify microstructure and morphology of the deposits. It is found that the deposits are composed of amorphous and nanocrystalline structure phases. Compared with the nickel sulfate solution, the amorphous/nanocrystalline alloys are more accessible to be obtained in carbonate solution under the same conditions as the sulfate solution. The internal stress between the deposit and the basement is inexistent with the tiny granules and well-proportioned grains at the coating surface. The stability of the alkaline nickel carbonate solution is much better than the sulfate solution, and the deposit performance is relatively better and easy to be controlled.

Synthesis and Characterization of Nanostructured Mechanical Cu-Fe-Co Alloy

2018 ◽  
Vol 941 ◽  
pp. 1232-1237
Author(s):  
Alisiya Biserova-Tahchieva ◽  
Isabel López-Jiménez ◽  
Núria Llorca-Isern
Keyword(s):  
Defect Density ◽  
Nanocrystalline Structure ◽  
High Energy ◽  
Magnetic Behaviour ◽  
X Ray Diffraction ◽  
X Ray ◽  
Soft Ferromagnetic ◽  
Hours Of Work ◽  
And Diffusion

Nanocrystalline structure of CuFeCo (50:25:25 wt%) alloy has been obtained by high energy mechanical milling from elemental metal powder mixture during large hours of work. Phase transformations and diffusion in the system subjected to heat treatment are discussed. Thermal stability at high temperatures is analysed and considered of importance for several applications. The nanostructure was studied by employing X-Ray diffraction and electron microscopy. It has been determined the reduction in crystallite size and the induced microstrain by the milling time. The solid solution achievement through the increment of defect density was confirmed by Mössbauer analysis. Magnetic behaviour was analysed through magnetization technique entailing their soft ferromagnetic behaviour related to the microstructural changes.

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