Influence of Thermal Treatment on the Appearance of a Three Step Martensitic Transformation in NiTi

1995 ◽  
Vol 05 (C8) ◽  
pp. C8-647-C8-652 ◽  
Author(s):  
L. Bataillard ◽  
R. Gotthardt
Keyword(s):  
Martensitic Transformation ◽  
Thermal Treatment

scholarly journals EFFICIENCY ADJUSTMENT OF STANDARD THERMAL TREATMENT OF 30HGSA STEEL

2016 ◽  
Vol 2016 (2) ◽  
pp. 121-128 ◽  
Author(s):  
Ирина Ворначева ◽  
Irina Vornacheva ◽  
Василий Муравьев ◽  
Vasiliy Muravev ◽  
Алексей Фролов ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Thermal Treatment ◽  
Strength Properties ◽  
Defective Structure ◽  
Bainitic Hardening

The efficiency of thermal treatment of 30HGSA steel is considered. The mode of bainitic hardening contributing to smoothing of steel defective structure a more complete martensitic transformation and, as a consequence, to the increase of plastic and strength properties is considered.

scholarly journals Magnetic and Magnetostrictive Properties of Ni50Mn20Ga27Cu3 Rapidly Quenched Ribbons

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5126
Author(s):  
Mihaela Sofronie ◽  
Mugurel Tolea ◽  
Bogdan Popescu ◽  
Monica Enculescu ◽  
Felicia Tolea
Keyword(s):  
Magnetic Field ◽  
Martensitic Transformation ◽  
Thermal Treatment ◽  
Austenite Phase ◽  
Transformation Temperatures ◽  
Strain Measurements ◽  
Rapid Solidification Technique ◽  
Phase Transition Temperatures ◽  
Ferromagnetic Shape Memory ◽  
Curie Temperatures

The influence of the rapid solidification technique and heat treatment on the martensitic transformation, magnetic properties, thermo- and magnetic induced strain and electrical resistivity is investigated for the Cu doped NiMnGa Heusler-based ferromagnetic shape memory ribbons. The martensitic transformation temperatures are unexpectedly low (below 90 K—which can be attributed to the disordered texture as well as to the uncertainty in the elements substituted by the Cu), preceded by a premartensitic transformation (starting at around 190 K). A thermal treatment slightly increases the transformation as well as the Curie temperatures. Additionally, the thermal treatment promotes a higher magnetization value of the austenite phase and a lower one in the martensite. The shift of the martensitic transformation temperatures induced by the applied magnetic field, quantified from thermo-magnetic and thermo-magnetic induced strain measurements, is measured to have a positive value of about 1 K/T, and is then used to calculate the transformation entropy of the ribbons. The magnetostriction measurements suggest a rotational mechanism in low fields for the thermal treated samples and a saturation tendency at higher magnetic fields, except for the temperatures close to the phase transition temperatures (saturation is not reached at 5 T), where a linear volume magnetostriction cannot be ruled out. Resistivity and magnetoresistance properties have also been measured for all the samples.

Structure and Shape Memory Effect in Annealed Ni-Ti-Co Strip Produced by Twin Roll Casting Technique

2009 ◽  
Vol 154 ◽  
pp. 59-64 ◽  
Author(s):  
Tomasz Goryczka
Keyword(s):  
Martensitic Transformation ◽  
Thermal Treatment ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Shape Recovery ◽  
Real Condition ◽  
Casting Technique ◽  
Multi Stage ◽  
Roll Casting ◽  
Twin Roll

The ternary Ni47Ti50Co3 alloy was produced using twin rolls casting technique. The strip was annealed at 3000C, 4000C or 5000C for 1 hour. Annealing was carried out in real condition without protection atmosphere. The strips revealed a multi-stage martensitic transformation. However, the origin of this multi-stage transformation is different in the as-cast strip when compare to the thermally treated samples. Thermal treatment increases amount of preferentially oriented grains and in consequence higher degree of the shape recovery can be obtained.

Pollutant Identification by Selected Area Electron Diffraction

1974 ◽  
Vol 32 ◽  
pp. 532-533
Author(s):  
R. E. Ferrell ◽  
G. G. Paulson ◽  
C. W. Walker
Keyword(s):  
Thermal Treatment ◽  
Electron Diffraction ◽  
Sample Preparation ◽  
Crystal Structures ◽  
Water Samples ◽  
Environmental Samples ◽  
Short Review ◽  
Selected Area Electron Diffraction ◽  
Multiple Component

Selected area electron diffraction (SAD) has been used successfully to determine crystal structures, identify traces of minerals in rocks, and characterize the phases formed during thermal treatment of micron-sized particles. There is an increased interest in the method because it has the potential capability of identifying micron-sized pollutants in air and water samples. This paper is a short review of the theory behind SAD and a discussion of the sample preparation employed for the analysis of multiple component environmental samples.

Development of Crystallinity in Turbostratic Boron Nitride Derived from Polymeric Precursors

1991 ◽  
Vol 49 ◽  
pp. 954-955
Author(s):  
X. Qiu ◽  
A. K. Datye ◽  
T. T. Borek ◽  
R. T. Paine
Keyword(s):  
Thermal Treatment ◽  
Boron Nitride ◽  
Diffraction Pattern ◽  
Polymeric Precursors ◽  
Polymer Precursors ◽  
Diffuse Ring

Boron nitride derived from polymer precursors is of great interest for applications such as fibers, coatings and novel forms such as aerogels. The BN is prepared by the polymerization of functionalized borazine and thermal treatment in nitrogen at 1200°C. The BN powders obtained by this route are invariably trubostratic wherein the sheets of hexagonal BN are randomly oriented to yield the so-called turbostratic modification. Fib 1a and 1b show images of BN powder with the corresponding diffraction pattern in fig. 1c. The (0002) reflection from BN is seen as a diffuse ring with occational spots that come from crystals of BN such as those shown in fig. 1b. The (0002) lattice fringes of BN seen in these powders are the most characteristic indication of the crystallinity of the BN.

In situ observation of the martensitic transformation in (Mg,Y)-PSZ

1986 ◽  
Vol 44 ◽  
pp. 500-501
Author(s):  
R-R. Lee
Keyword(s):  
Martensitic Transformation ◽  
High Strength ◽  
Nucleation And Growth ◽  
In Situ Observation ◽  
Considerable Potential ◽  
Transmission Electron ◽  
Structural Applications ◽  
Applied Stresses ◽  
Kinetics Of

Partially-stabilized ZrO2 (PSZ) ceramics have considerable potential for advanced structural applications because of their high strength and toughness. These properties derive from small tetragonal ZrO2 (t-ZrO2) precipitates in a cubic (c) ZrO2 matrix, which transform martensitically to monoclinic (m) symmetry under applied stresses. The kinetics of the martensitic transformation is believed to be nucleation controlled and the nucleation is always stress induced. In situ observation of the martensitic transformation using transmission electron microscopy provides considerable information about the nucleation and growth aspects of the transformation.

Evidence for ordered Fe3Ni

1987 ◽  
Vol 45 ◽  
pp. 216-217
Author(s):  
K.B. Reuter ◽  
D.B. Williams ◽  
J.I. Goldstein
Keyword(s):  
Experimental Data ◽  
Martensitic Transformation ◽  
Electron Diffraction ◽  
Room Temperature ◽  
Direct Evidence ◽  
Transformation Product ◽  
Iron Meteorites ◽  
X Ray ◽  
Ni Content ◽  
Temperature Transformation

In the Fe-Ni system, although ordered FeNi and ordered Ni3Fe are experimentally well established, direct evidence for ordered Fe3Ni is unconvincing. Little experimental data for Fe3Ni exists because diffusion is sluggish at temperatures below 400°C and because alloys containing less than 29 wt% Ni undergo a martensitic transformation at room temperature. Fe-Ni phases in iron meteorites were examined in this study because iron meteorites have cooled at slow rates of about 10°C/106 years, allowing phase transformations below 400°C to occur. One low temperature transformation product, called clear taenite 2 (CT2), was of particular interest because it contains less than 30 wtZ Ni and is not martensitic. Because CT2 is only a few microns in size, the structure and Ni content were determined through electron diffraction and x-ray microanalysis. A Philips EM400T operated at 120 kV, equipped with a Tracor Northern 2000 multichannel analyzer, was used.

Structure of a new orthorhombic phase in NiTi: Mn shape memory alloys

1990 ◽  
Vol 48 (4) ◽  
pp. 1000-1001
Author(s):  
Jenö Beyer ◽  
Lajos Tóth
Keyword(s):  
Martensitic Transformation ◽  
Structural Changes ◽  
High Vacuum ◽  
Intermetallic Phase ◽  
Orthorhombic Phase ◽  
Transformation Process ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Crystallographic Structures ◽  
Ternary Additions

The structural changes during reversible martensitic transformation of near-equiatomic NiTi alloys can best be studied in TEM at around room temperature. Ternary additions like Mn offer this possibility by suppressing the Ms temperature below RT. Besides the stable intermetallic phases (Ti2Ni, TiNi, TiNi3) several metastable phases with various crystallographic structures (rhombohedral, hexagonal, monoclinic, cubic) have also been reported to precipitate due to suitable annealing procedures.TiNi:Mn samples with 0.9 and 1.3 at% Mn were arc melted in argon atmosphere and homogenized at 948 °C for 72 hours in high vacuum in an infrared furnace. After spark cutting slices of 0.2 mm, TEM specimens were prepared by electrochemical polishing with the twin-jet technique in methanol - perchloric acid electrolyte. The TEM study was carried out in a JEOL 200 CX analytical electron microscope.In this paper a new intermetallic phase is reported which has been observed in both samples by TEM during the martensitic transformation process.

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