Amorphous shear bands in deformed TiNi alloy

Tat’yanin, E. V.; Borovikov, N. F.; Kurdyumov, V. G.; Indenbom, V. L.

doi:10.1134/1.1130038

Cited by 12 publications

(5 citation statements)

References 7 publications

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“…Therefore, the static dislocation densities deter- mined post-mortem in the crystalline phase make it rather unlikely that a homogeneous formation of an amorphous phase by defect accumulation exceeding the stability limit could occur. It was proposed that in the developing shear bands the dislocation density could be higher than that expected by static defect accumulation [19]. Therefore the present observations of an inhomogeneous occurrence of the amorphous phase in the form of shear bands indicate that localized in the shear bands the dynamic accumulation of defects can lead to densities locally exceeding the stability limit.…”

Section: Amorphization Of Niti By Severe Plastic Deformationmentioning

confidence: 89%

TEM of nanostructured metals and alloys

Karnthaler

Waitz

Rentenberger

et al. 2004

Materials Science and Engineering: A

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Section: Amorphization Of Niti By Severe Plastic Deformationmentioning

confidence: 89%

TEM of nanostructured metals and alloys

Karnthaler

Waitz

Rentenberger

et al. 2004

Materials Science and Engineering: A

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“…It is proved that in steels and alloys, the megaplastic deformation and phase transition happen is often accompanied by phase transition precipitation and dissolution of phases, martensitic transformation, amorphization) These transitions occur in intermetallic compounds or multicomponent systems. [28][29][30] The effects of above-cited lubricants and number of ECAP passes on inner diameter are presented in Figure 8, which is deduced that inner diameter enhances in ECAP process. Also, it is proved that the sample exposed to different number of ECAP passes exhibits higher hardness.…”

Section: Effect Of Height Reductionmentioning

confidence: 99%

Frictional behavior of severe plastic deformed copper sample by using friction calibration curves

Javdani

Aghaei

Asadollahi

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part C:

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Equal Channel Angular Pressing (ECAP) known as one of the most significant methods involving in severe plastic deformation. There are not many investigations which focus on the design of dies and its analysis by FEM, considering friction coefficients as die geometry parameters; likewise, only few studies have been reported in which the effect of die shape has been analyzed, for example. One of the challenging problems in industrialization of ECAP is designing and manufacturing of die. To avoid trial and error in the next designs, the measurement of right friction coefficient plays a key role, which is used in finite element method to prevent doing experimental test. The main objective of this study was to investigate and find generalized friction calibration curves utilizing the ring compression test. To perform the ring compression test, which is oxygen-free copper with 99.7%, (BS EN 15079 standard) the standard ring specimen ratio of 6:3:2 was used. With use of different lubricants during the ring compression test the relations between friction coefficients and changes of inner and outer diameters was revealed. To solve complicated plasticity equations with complex geometries and boundary conditions with various friction coefficients, finite element method was used. To use more accurate frictional coefficient values with considering different ECAP passes, friction calibration curves were updated.

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“…It is well known that NiTi is susceptible to amorphization as a result of various processing treatments and the formation of an amorphous phase was detected, for example in the case of ion beam mixing [31], mechanical alloying [32], ion implantation [33], shot peening [34], as well as cold rolling [24,26,35,36] and shear deformation [37]. However in these publications the amorphization of NiTi was [12] we demonstrate the formation of bulk amorphous NiTi alloy by HPT and the formation of a homogenous nanostructure by its crystallization and growth under controlled heating and annealing conditions.…”

Section: Discussionmentioning

confidence: 99%

Annealing behaviour of nanocrystalline NiTi (50 at% Ni) alloy produced by high-pressure torsion

Singh

Rösner

Prokofyev

et al. 2011

Philosophical Magazine

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International audienceAn equiatomic nanocrystalline NiTi alloy, deformed by high-pressure torsion (HPT) was investigated. The as-prepared bulk NiTi alloy consists of both amorphous and nanocrystalline phases. Crystallization and structural changes during annealing were investigated by differential scanning calorimetry (DSC), X-ray diffraction and transmission electron microscopy. The DSC thermograms and X-ray analyses reveal stress relaxation and partial crystallization below 500 K while grain growth of the nanocrystals occurs predominantly after heating to temperatures above 573 K. Along with the amorphous phase crystallization, a continuous growth of pre-existing nanocrystals that are retained after HPT is observed. The DSC signals observed during continuous heating experiments indicate an unusually large separation between the crystallization and the growth stages. A detailed analysis of the evolution of the enthalpy release upon annealing reveals reproducibly non-monotonous trends with annealing temperature that cannot be explained solely with nucleation and growth of crystalline volume fractions. Instead, the results can be rationalized by assuming a reverse amorphization process occuring during annealing at 523 K. This behavior, that also causes a large variation of the nanocrystals size after annealing at higher temperatures, is discussed with respect to the nanoscale microstructural heterogeneity after initial deformation processing

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Amorphous shear bands in deformed TiNi alloy

Cited by 12 publications

References 7 publications

TEM of nanostructured metals and alloys

TEM of nanostructured metals and alloys

Frictional behavior of severe plastic deformed copper sample by using friction calibration curves

Annealing behaviour of nanocrystalline NiTi (50 at% Ni) alloy produced by high-pressure torsion

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