PHONON SPECIFIC HEAT NEAR THE MARTENSITIC TRANSFORMATION IN A CUBIC CuZnAl ALLOY

1978 ◽  
Vol 39 (C6) ◽  
pp. C6-1033-C6-1034 ◽  
Author(s):  
D. Abbe ◽  
R. Caudron ◽  
P. Costa
Keyword(s):  
Martensitic Transformation ◽  
Specific Heat

The specific heat of lithium from 20 to 300 °K: the martensitic transformation

1960 ◽  
Vol 254 (1279) ◽  
pp. 444-454 ◽  
Keyword(s):  
Martensitic Transformation ◽  
Specific Heat ◽  
Atomic Weight ◽  
Phase Region ◽  
Two Phase ◽  
Self Diffusion ◽  
Debye Temperatures ◽  
Order Of Magnitude ◽  
Two Phases ◽  
Heat Of Transformation

Measurements on lithium of atomic weight 6·945 are reported. A thermal study of the martensitic transformation showed a large specific-heat anomaly in the reversion region and a specific heat dependent upon thermal history in the two-phase region. The high-temperature end of the reversion anomaly shows time effects which suggest that the process here is controlled by a spectrum of activation energies of the same order of magnitude as that for self diffusion. With some assumptions the heat of transformation from hexagonal closepacked to body-centered cubic lithium is deduced to be about 14 cal/g atom and the Debye temperatures of the two phases at 60 °K are 390 and 371 °K respectively. The entropy at 298·15 °K is 6·95 ±0·04 cal/°K g atom.

The specific heat of sodium from 20 to 300 °K: the martensitic transformation

1960 ◽  
Vol 254 (1279) ◽  
pp. 433-443 ◽  
Keyword(s):  
Martensitic Transformation ◽  
Specific Heat ◽  
Phase Region ◽  
Two Phase ◽  
Cast Sample ◽  
Hexagonal Close Packed ◽  
Debye Temperatures ◽  
Significant Difference ◽  
Two Phases ◽  
Heat Of Transformation

Measurements on a cast sample and an extruded sample are reported. There is no significant difference in behaviour. No anomaly of the type reported by Dauphinee et al. (1954) was found. A thermal study of the martensitic transformation showed a large specific-heat anomaly in the reversion region and a specific heat dependent on thermal history in the two-phase region. The heat of transformation from hexagonal close-packed to body-centred cubic sodium is deduced to be about 10 cal/g atom and the Debye temperatures of the two phases at 20 °K to be 160 and 153 °K respectively. The entropy at 298.15 °K is 12.24 ± 0.12 cal/°K g atom.

THE SPECIFIC HEAT OF A LITHIUM–MAGNESIUM ALLOY. THE MARTENSITIC TRANSFORMATION

1960 ◽  
Vol 38 (1) ◽  
pp. 25-31 ◽  
Author(s):  
Douglas L. Martin
Keyword(s):  
High Temperature ◽  
Magnesium Alloy ◽  
Martensitic Transformation ◽  
Specific Heat ◽  
Heat Content ◽  
The Body ◽  
Cubic Phase ◽  
Body Centered Cubic

The specific heat of an alloy of lithium with 0.95 at.% magnesium has been measured from 20° to 300 deg;K. The specific heat of the body-centered cubic phase is less than that calculated from the Kopp–Neumarin rule. A specilic heat anomaly, due to the martensitic transformation, is observed and has almost the same heat content as the corresponding anomaly for pure lithium but the high-temperature end is of signilicantly different shape.

Electronic structure and the martensitic transformation in β-phase Ni-Al alloys:Al27NMR and specific-heat measurements

1992 ◽  
Vol 46 (17) ◽  
pp. 10563-10572 ◽  
Author(s):  
Silvia Rubini ◽  
Costas Dimitropoulos ◽  
Sergio Aldrovandi ◽  
Ferdinando Borsa ◽  
David R. Torgeson ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Martensitic Transformation ◽  
Specific Heat ◽  
Β Phase

Anomalies in Physical Properties Related to the Stability of the B2-Phase in Ti-Ni-Co Shape Memory Alloys

2005 ◽  
Vol 475-479 ◽  
pp. 1977-1982 ◽  
Author(s):  
Mi Seon Choi ◽  
Takashi Fukuda ◽  
Tomoyuki Kakeshita
Keyword(s):  
Electrical Resistivity ◽  
Magnetic Susceptibility ◽  
Martensitic Transformation ◽  
Specific Heat ◽  
Nucleation And Growth ◽  
Electronic Specific Heat ◽  
Transformation Behavior ◽  
First Order ◽  
The Stability ◽  
Specific Heat Coefficient

Martensitic transformation behavior of a series of Ti-(50-x)Ni-xCo at% alloys (x = 4, 8, 12, 16, 20) has been examined by electrical resistivity, magnetic susceptibility and specific heat measurements, in order to know the phase stability of the B2-type structure. The 4Co and 8Co alloys exhibit a typical first order B2-R-B19' transformation. The 12Co alloy probably transforms to the R-phase, but its microstructure is composed of small domains with about 10 nm in diameter, being quite different from the microstructure of a typical R-phase formed by nucleation and growth. The 16Co and the 20Co alloys do not show any martensitic transformation but anomalies of the electrical resistivity and magnetic susceptibility being similar to those of the 12Co alloy appear in these alloys. The diffuse scattering of 1/3<110> is also observed in the 16Co alloy. The Debye temperature decreases and electronic specific heat coefficient increases with increasing Co content.

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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