Orthorhombic Martensite, Intermetallic Precipitates and Retained Austenite in Ti-Rich Ti(Ni+Cu) Sputtered thin Films

1991 ◽  
Vol 246 ◽  
Author(s):  
L. Chang ◽  
D. S. Grummon
Keyword(s):  
Thin Films ◽  
Martensite Transformation ◽  
Pure Titanium ◽  
Titanium Content ◽  
Martensite Phase ◽  
Scanning Calorimetry ◽  
Orthorhombic Martensite ◽  
Layer Thickness Ratio ◽  
Fluorescence Measurements ◽  
Transformation Enthalpy

AbstractPeriodic multilayered titanium-rich Ni-Ti thin films were prepared by magnetron sputtering from alternating Ni45Ti50Cu5 alloy and pure titanium targets, with an alloy-layerfl'i-layer thickness ratio of 9:1. The microstructure, martensite transformation behavior, and precipitate and defect structures were studied in films which had been annealed at 923K for one hour and furnace cooled at <20 K/min. Energy dispersive X-ray fluorescence measurements showed that the resulting films had a hyperstoichiometric titanium content of approximately 51 atomic percent. Ti2Ni precipitates were found in the annealed structures which were oriented with [1 1 0 ]Ti2Ni parallel to [110]B2 and (001)Ti2Ni parallel within +/− 10 to (001)B2. Differential scanning calorimetry (DSC) revealed an unusually low transformation enthalpy for the martensite reaction in the film (9.1 J/g as opposed to 20.7 J/g for the alloy sputtering target), and a significant fraction of residual B2 austenite was found at temperatures well below the nominal Mf. The martensite transformation was found to occur in two steps involving, on cooling, the initial formation of an orthorhombic martensite prior to transformation to the monoclinic martensite phase at low temperature.

Effect of Zr Addition on Martensitic Transformation in TiMoSn Alloy

2014 ◽  
Vol 922 ◽  
pp. 137-142 ◽  
Author(s):  
Kazuki Endoh ◽  
Masaki Tahara ◽  
Tomonari Inamura ◽  
Hee Young Kim ◽  
Shuichi Miyazaki ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Alloy System ◽  
Martensite Phase ◽  
Lattice Parameters ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Orthorhombic Martensite ◽  
Β Phase ◽  
Zr Addition

The effects of Zr addition on martensitic transformation and the lattice parameters of α” (orthorhombic) martensite and β (bcc) phase were investigated in Ti-3mol%Mo-6mol%Sn based alloys containing up to 4mol%Zr using θ-2θ X-ray diffraction measurement (XRD) and differential scanning calorimetry (DSC). It was found by XRD that orthorhombic α” martensite phase is formed when Zr content is 0 to 2mol% while bcc β phase also existed in the alloy containing 2 to 4mol%Zr. Based on the lattice parameters in α” martensite and β parent phases evaluated, the transformation strains between α” and β phase calculated become slightly small with increasing Zr content. DSC revealed that, with increasing Zr content, reverse martensitic transformation start and finish temperatures decreased down to 410K with a rate of-30K/mol%Zr. It is concluded in the Ti-Mo-Sn alloy system that Zr addition stabilizes β phase and that Zr addition is effective to control martensitic transformation temperature without changing the transformation strains largely.

Kinetics of Intermetallic Formation in Free Standing Cu/Mg Multilayer Thin Films

1992 ◽  
Vol 260 ◽  
Author(s):  
B. Arcof ◽  
L. A. Clevenger ◽  
S. P. Murarka ◽  
J. M. E. Harper ◽  
C. Cabrai
Keyword(s):  
Thin Films ◽  
Activation Energy ◽  
Layer Thickness ◽  
Reaction Times ◽  
Thickness Ratio ◽  
Formation Mechanisms ◽  
Multilayer Thin Films ◽  
Scanning Calorimetry ◽  
Free Standing ◽  
Layer Thickness Ratio

ABSTRACTDifferential scanning calorimetry (DSC) has been used to study the temperatures, kinetics and phase formation mechanisms in Cu/Mg multilayer thin films. When the Cu:Mg layer thickness ratio was 1:4, CuMg2 was the only phase that formed. Cu/Mg films with a layer thickness ratio of 1:1 first form CuMg2 at 215°C with an activation energy of 1.0 ± 0.04 eV and then Cu2Mg at 380°C with an activation energy of 0.73 ± 0.04 eV. The temperatures at which the two phases form decrease as the layer thicknesses decrease due to the shorter reaction times needed in thinner films. The constant scan rate DSC data from films with a layer thickness ratio of 1:1 show three exothermic peaks. The first peak is extremely sharp and results from the formation of isolated nuclei of CuMg2 at the Cu/Mg interface. The formation of CuMg2 is thus shown to be nucleation controlled. The second peak is a growth peak due to the heat released during the growth of CuMg2. The third peak corresponds to the formation and growth of Cu2Mg.

Observation by HVEM of the martensite transformation and the superconducting transition in Nb3Sn

1988 ◽  
Vol 46 ◽  
pp. 788-789
Author(s):  
M. A. Kirk ◽  
M. C. Baker ◽  
B. J. Kestel ◽  
H. W. Weber
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Superconducting State ◽  
Martensite Transformation ◽  
Sputter Deposition ◽  
Diffusion Reaction ◽  
Solute Diffusion ◽  
Superconducting Transition ◽  
Twin Boundaries ◽  
Martensite Structure

It is well known that a number of compound superconductors with the A15 structure undergo a martensite transformation when cooled to the superconducting state. Nb3Sn is one of those compounds that transforms, at least partially, from a cubic to tetragonal structure near 43 K. To our knowledge this transformation in Nb3Sn has not been studied by TEM. In fact, the only low temperature TEM study of an A15 material, V3Si, was performed by Goringe and Valdre over 20 years ago. They found the martensite structure in some foil areas at temperatures between 11 and 29 K, accompanied by faults that consisted of coherent twin boundaries on {110} planes. In pursuing our studies of irradiation defects in superconductors, we are the first to observe by TEM a similar martensite structure in Nb3Sn.Samples of Nb3Sn suitable for TEM studies have been produced by both a liquid solute diffusion reaction and by sputter deposition of thin films.

Influence of material parameters on 2D-martensitic transformation based on the phase-field finite-element method

2019 ◽  
Vol 116 (6) ◽  
pp. 614
Author(s):  
Li Chang ◽  
Gao Jingxiang ◽  
Zhang Dacheng ◽  
Chen Zhengwei ◽  
Han Xing
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Phase Transformation ◽  
Martensitic Transformation ◽  
Phase Field ◽  
Martensite Transformation ◽  
Transformation Process ◽  
Martensite Phase ◽  
Phase Field Method ◽  
Element Method

Obtaining an accurate microscopic representation of the martensitic transformation process is key to realizing the best performance of materials and is of great significance in the field of material design. Due to the martensite phase transformation is rapidly, the current experimental is hard to capture all the information in the Martensite phase transformation process. Combining the phase-field method with the finite-element method, a model of martensitic transformation from a metastable state to a steady state is established. The law of a single martensite nucleus during martensitic transformation is accurately described. By changing the key materials that affect martensite transformation and the phase-field parameters, the effects of the parameters on the single martensitic nucleation process are obtained. This study provides an important theoretical basis for effectively revealing the essence of martensite transformation and can determine effective ways to influence martensite transformation, obtain the optimal parameters and improve the mechanical properties of such materials.

In Situ Produced MMC Layer by Laser Melt Injection

2010 ◽  
Vol 649 ◽  
pp. 61-66
Author(s):  
Zoltán Kálazi ◽  
Viktória Janó ◽  
Gábor Buza
Keyword(s):  
Carbon Content ◽  
Composite Layer ◽  
Pure Titanium ◽  
Base Material ◽  
Titanium Content ◽  
Steel Sample ◽  
Low Carbon ◽  
The Matrix ◽  
Ti Powder

Tungsten (W) based alloy composite layer reinforced with TiC particles has been successfully prepared on unalloyed steel sample by LMI technology. In order to obtain in situ produced TiC reinforcement, pure titanium has been introduced to the melt pool. WC powder was added for increasing the carbon content of the layer in order to avoid the softening of the matrix (with low carbon content) during TiC formation. The present study aims to investigate the optimum amount of injected WC and Ti powder to improve wear resistance and hardness of the layer. Samples were investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The maximum hardness of the layer has been reached ~900HV in case of 2-4wt% of titanium content. Ti has been collected all of the carbon from the matrix when titanium content was 9,6wt%, which resulted that the austenite and (Fe,W)6C phases have been disappeared. Only α-Fe and TiC phases were presented in the layer. The hardness of the layer reduced to the hardness of the base material.

scholarly journals The Effect of Drawing Deformation Rate Induced Inhomogeneous Local Distortion on Phase Transformation of 304H Stainless Wire

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1304
Author(s):  
Qinhua Xu ◽  
Zhixian Peng ◽  
Jianxin Zhu ◽  
Mingyang Li ◽  
Yong Zong ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Phase Transformation ◽  
Heat Generation ◽  
Martensite Transformation ◽  
Local Strain ◽  
Cold Drawing ◽  
Element Distribution ◽  
Martensite Phase ◽  
Single Strain ◽  
Area Reduction

The micro/macro magnetic properties, local element distribution, martensite transformation, and mechanical properties of 304H stainless wires are determined for two cold drawing chains. Finite element simulations are used to analyse the local strain and heat generation. The results show that there is obvious inhomogeneity in the magnetic properties, strain/stress relationship, and strain-induced heat within the drawn wires. Comparing wires with the same total strain, a larger area reduction of previous drawing processes contributes to a higher volume of the martensite phase, while a smaller area reduction of the first process results in an inhibited phase transformation. A higher single strain in the first drawing process leads to additional heat generation at the subsurface of the wire, which would eventually retard the martensite transformation. The inhomogeneous deformation-induced differences in the grain size affect the stability of austenite and transform the final martensite.

Processing and Characterization of Thermoplastic Polyurethane Nanocomposite Thin Films

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Anandh Balakrishnan ◽  
Mrinal C. Saha
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Molecular Weight ◽  
Optical Microscopy ◽  
Carbon Nanofiber ◽  
Droplet Diameter ◽  
Thermoplastic Polyurethane ◽  
Scanning Calorimetry ◽  
Ultrasound Assisted ◽  
Set Up

In this article, we have set up protocols for fabricating thermoplastic polyurethane thin films of about 30 μm (neat polyurethane and carbon nanofiber (CNF) containing polyurethane) via ultrasound assisted atomization at 20 kHz. From processing to thin film peel off, we have set up procedures for fabricating our samples. Using optical microscopy, we have examined the manufacturing of these films from a droplet diameter perspective. Our optical microscopy results indicate that the final film microstructure was directly dependent on the physical properties of the neat/CNF reinforced solution. Mechanical testing of these films was then carefully carried out using a dynamic mechanical analyzer (DMA) unit utilizing a specialized thin film test clamp fixture. These test results were compared with control cast films fabricated from the same solutions. For the similar extensions, we observed a drastic increase in the softness of the atomized film. We surmise that the ultrasound assisted droplet generation concurrent with secondary atomization and evaporation could have resulted in reduction of the molecular weight of the polyurethane in our atomized samples relative to the neat ones. Differential scanning calorimetry (DSC) scans have been conducted to confirm the changes in molecular weight. Although results were inconclusive there is evidence of exotherms at 49C in our atomized samples suggested of changes to molecular weight distribution.

Effect of Manganese on Titanium Thin Films Adhesion Deposited on Steel Substrates

2012 ◽  
Vol 326-328 ◽  
pp. 583-586
Author(s):  
R. Gheriani ◽  
Raouf Mechiakh
Keyword(s):  
Thin Films ◽  
Annealing Temperature ◽  
Vacuum Annealing ◽  
Pure Titanium ◽  
Nucleation And Growth ◽  
Thin Solid Films ◽  
X Ray ◽  
Solid Films ◽  
Titanium Thin Films ◽  
Steel Substrates

The mainly property of thin solid films technologies is their adhesion to the substrates. Because of its good wear resistance and its low coefficient of friction against steel, TiC is an attractive coating material for wear applications such as bearing components. The adhesion of TiC coatings, however suffers from insufficient reproducibility, which is probably due to uncontrolled process parameters. In our work pure titanium thin films of approximately 0.6 µm in thickness were prepared on 100C6 stainless steel substrates by cathodic sputtering. The samples were subjected to secondary vacuum annealing at a temperature between 400 and 1000°C for 30 min. The reaction between substrates and thin films was characterized using an x-ray diffractometer (XRD). Surface morphology and elements diffusion evaluations were carried out by scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). The interaction substrates-thin films is accompanied by nucleation and growth of titanium carbide as a function of annealing temperature. By the SEM and EDS results, it appears clearly that the diffusion of manganese to the external layers leads to the destruction of adhesion especially at high temperatures.

Self-Accommodation Mechanisms for Orthorhombic Martensite Formation in Sputtered Thin Films of Thermoelastic Ti(Nicu)

1993 ◽  
Vol 311 ◽  
Author(s):  
L. Chang ◽  
D. S. Grummon
Keyword(s):  
Thin Films ◽  
Orthorhombic Phase ◽  
Austenite Phase ◽  
Simultaneous Occurrence ◽  
Transmission Microscopy ◽  
Fine Grained ◽  
Orthorhombic Martensite ◽  
Austenite Grain ◽  
Lower Temperature ◽  
Accommodation Mechanism

ABSTRACTDirect observation of the self-accommodation morphology for orthorhombic martensite in Ti51.0Ni44.4Cu4.6 thin films has been accomplished by transmission microscopy of fine grained (<2μm) material prepared by triode magnetron sputtering. The films were observed to undergo, on cooling, two separate thermoelastic transformations in which the B2 austenite phase first transformed to an orthorhombic martensite with a =.291 nm, b =.425 nm and c =.450 nm followed by transformation to the monoclinic phase at lower temperature. The R-phase transformation was suppressed. Single grains contained as many as eight crystallographic variants of the orthorhombic phase, the majority of which were shaped as parallelograms bounded by {111}Ortho twin planes. The local self-accommodation mechanism produced combinations in which three adjacent variants shared a common {111}B2 pole. Although the majority of B19 variant domains accommodated themselves through {111}Ortho type twinning, a second accommodation mechanism, involving two sets of band-like martensite variants, bounded by {011}ortho twin planes, was also observed. Simultaneous occurrence of the {111}ortho and {011}ortho twinning modes, wihtin a single austenite grain, was not observed.

The Study of Ultrasonic Dynamic Elastic Modulus of TiNiFe Shape Memory Alloy in Heating Process

2009 ◽  
Vol 79-82 ◽  
pp. 1699-1702
Author(s):  
Xiao Peng Gao ◽  
Fu Shun Liu
Keyword(s):  
Phase Transformation ◽  
Elastic Modulus ◽  
Test Temperature ◽  
Martensite Transformation ◽  
Martensite Phase ◽  
Austenite Phase ◽  
Dynamic Elastic Modulus ◽  
Heating Process ◽  
Static Tensile ◽  
Tensile Elastic Modulus

The phase transformation characteristics, the dynamic elastic modulus and the static tensile elastic modulus of Ti50Ni47.5Fe2.5 alloy were investigated. It is found that, the two mutations in the dynamic elastic modulus is caused by reverse martensite phase transformation and austenite phase transformation respectively; Static tensile test can not reflect the intrinsic elastic modulus when the test temperature is close to martensite transformation temperature(Ms). The static elastic modulus and the dynamic elastic modulus have the same trend when the test temperature is enough higher than Ms.

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