scholarly journals Nanoscale twinning in Fe–Mn–Al–Ni martensite: a backscatter Kikuchi diffraction study

2021 ◽  
Vol 54 (1) ◽  
Author(s):  
Peter D. B. Fischer ◽  
Stefan Martin ◽  
Alexander Walnsch ◽  
Martin Thümmler ◽  
Mario J. Kriegel ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory ◽  
Diffraction Study ◽  
Face Centered Cubic ◽  
Ni Alloys ◽  
Heat Treated ◽  
Iron Based ◽  
Face Centered ◽  
Ice Water ◽  
Interstitial Elements

Iron-based Fe–Mn–Al–Ni shape-memory alloys are of rather low materials cost and show remarkable pseudoelastic properties. To further understand the martensitic transformation giving rise to the pseudoelastic properties, different Fe–Mn–Al–Ni alloys have been heat treated at 1473 K and quenched in ice water. The martensite, which is formed from a body-centred cubic austenite, is commonly described as face-centered cubic (f.c.c.), even though there are also more complex, polytypical descriptions of martensite. The presently studied backscatter Kikuchi diffraction (BKD) patterns have been evaluated, showing a structure more complex than simple f.c.c. This structure can be described by nanoscale twins, diffracting simultaneously in the exciting volume. The twinned structure shows a tetragonal distortion, not uncommon for martensite in spite of the lack of interstitial elements. These features are evaluated by comparing the measured BKD patterns with dynamically simulated ones.

scholarly journals Effect of Sm Doping on the Microstructure, Mechanical Properties and Shape Memory Effect of Cu-13.0Al-4.0Ni Alloy

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4007
Author(s):  
Qimeng Zhang ◽  
Bo Cui ◽  
Bin Sun ◽  
Xin Zhang ◽  
Zhizhong Dong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Strengthening Effect ◽  
Face Centered Cubic ◽  
Compressive Fracture ◽  
Fine Grain ◽  
Fine Grain Strengthening ◽  
Face Centered

The effects of rare earth element Sm on the microstructure, mechanical properties, and shape memory effect of the high temperature shape memory alloy, Cu-13.0Al-4.0Ni-xSm (x = 0, 0.2 and 0.5) (wt.%), are studied in this work. The results show that the Sm addition reduces the grain size of the Cu-13.0Al-4.0Ni alloy from millimeters to hundreds of microns. The microstructure of the Cu-13.0Al-4.0Ni-xSm alloys are composed of 18R and a face-centered cubic Sm-rich phase at room temperature. In addition, because the addition of the Sm element enhances the fine-grain strengthening effect, the mechanical properties and the shape memory effect of the Cu-13.0Al-4.0Ni alloy were greatly improved. When x = 0.5, the compressive fracture stress and the compressive fracture strain increased from 580 MPa, 10.5% to 1021 MPa, 14.8%, respectively. When the pre-strain is 10%, a reversible strain of 6.3% can be obtained for the Cu-13.0Al-4.0Ni-0.2Sm alloy.

Investigation of Heat Treated Electrodeposited CoNiFe on Microstructure and Hardness

2015 ◽  
Vol 1113 ◽  
pp. 56-61
Author(s):  
Nor Azrina Resali ◽  
Koay Mei Hyie ◽  
M.N. Berhan ◽  
C.M. Mardziah
Keyword(s):  
Heat Treatment ◽  
Heat Treatment Temperature ◽  
Treatment Temperature ◽  
Crystallographic Structure ◽  
Face Centered Cubic ◽  
Heat Treated ◽  
Hardness Property ◽  
Finishing Process ◽  
The Face ◽  
Face Centered

In this research, heat treatment is the final finishing process applied on nanocrystalline CoNiFe to improve microstructure for good hardness property. Nanocrystalline CoNiFe has been synthesized using the electrodeposition method. This study investigated the effect of heat treatment at 500°C, 600°C, 700°C and 800°C on electrodeposited nanocrystalline CoNiFe. The heat treatment process was performed in the tube furnace with flowing Argon gas. By changing the heat treatment temperature, physical properties such as phase and crystallographic structure, surface morphology, grain size and hardness of nanocrystalline CoNiFe was studied. The nanocrystalline CoNiFe phase revealed the Face Centered Cubic (FCC) and Body Centered Cubic (BCC) crystal structure. FESEM micrographs showed that the grain sizes of the coatings were in the range of 78.76 nm to 132 nm. Dendrite shape was found in the microstructure of nanocrystalline CoNiFe. The nanocrystalline CoNiFe prepared in heat treatment temperature of 700°C, achieved the highest hardness of 449 HVN. The surface roughness of nanocrystalline CoNiFe heated at 700°C was found to be smaller than other temperatures.

scholarly journals Effect of Heat Treatment Temperature on Martensitic Transformation and Superelasticity of the Ti49Ni51 Shape Memory Alloy

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2539 ◽  
Author(s):  
Peiyou Li ◽  
Yongshan Wang ◽  
Fanying Meng ◽  
Le Cao ◽  
Zhirong He
Keyword(s):  
Heat Treatment ◽  
Martensitic Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Thermal Hysteresis ◽  
Treatment Temperature ◽  
Heat Treated ◽  
Different Temperatures ◽  
Tini Phase ◽  
Rapidly Solidified

The martensitic transformation and superelasticity of Ti49Ni51 shape memory alloy heat-treatment at different temperatures were investigated. The experimental results show that the microstructures of as-cast and heat-treated (723 K) Ni-rich Ti49Ni51 samples prepared by rapidly-solidified technology are composed of B2 TiNi phase, and Ti3Ni4 and Ti2Ni phases; the microstructures of heat-treated Ti49Ni51 samples at 773 and 823 K are composed of B2 TiNi phase, and of B2 TiNi and Ti2Ni phases, respectively. The martensitic transformation of as-cast Ti49Ni51 alloy is three-stage, A→R→M1 and R→M2 transformation during cooling, and two-stage, M→R→A transformation during heating. The transformations of the heat-treated Ti49Ni51 samples at 723 and 823 K are the A↔R↔M/A↔M transformation during cooling/heating, respectively. For the heat-treated alloy at 773 K, the transformations are the A→R/M→R→A during cooling/heating, respectively. For the heat-treated alloy at 773 K, only a small thermal hysteresis is suitable for sensor devices. The stable σmax values of 723 and 773 K heat-treated samples with a large Wd value exhibit high safety in application. The 773 and 823 K heat-treated samples have large stable strain–energy densities, and are a good superelastic alloy. The experimental data obtained provide a valuable reference for the industrial application of rapidly-solidified casting and heat-treated Ti49Ni51 alloy.

Effect of Annealing Conditions on Microstructure Evolution of NiMnFeGa Shape Memory Thin Film

2010 ◽  
Vol 150-151 ◽  
pp. 1745-1749
Author(s):  
Hai Bo Wang ◽  
Li Ma ◽  
Wei Cai
Keyword(s):  
Thin Film ◽  
Shape Memory ◽  
Microstructure Evolution ◽  
Face Centered Cubic ◽  
Free Standing ◽  
Annealing Conditions ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Face Centered ◽  
Ferromagnetic Shape Memory

The microstructure evolution of sputtered polycrystalline Ni54.75Mn13.25Fe7Ga25 ferromagnetic shape memory thin film annealed under different conditions is studied. Microstructure of different annealed films was studied using Transmission Electron Microscope (TEM) and corresponding selected area electron diffraction (SAED) patterns. The result shows that in the microstructure of as-deposited Ni54.75Mn13.25Fe7Ga25 free-standing film, after annealed at 1073 K for different time, the crystalline grain grows up with the increase of the annealing time. By analysis of the SAED patterns, the structure of the thin films change from face-centered cubic austenite to orthorhombic structure martensite compared between the film annealed at 1073 K for 10 mins, 1hr, 4 hrs, and 24 hrs respectively. It indicated that the heat treatment is an effective method of crystallizing behavior for the thin film.

Hydrogen Enhances Shape Memory Effect of a Ferrous Face-Centered Cubic Alloy

2020 ◽  
Vol 51 (9) ◽  
pp. 4439-4441
Author(s):  
Motomichi Koyama ◽  
Chunxi Hao ◽  
Eiji Akiyama ◽  
Kaneaki Tsuzaki
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Face Centered Cubic ◽  
Face Centered

A neutron diffraction study on a typical highly defective ceria–yttria solid solution

2002 ◽  
Vol 17 (4) ◽  
pp. 278-280 ◽  
Author(s):  
Keka R. Chakraborty ◽  
S. V. Chavan ◽  
A. K. Tyagi
Keyword(s):  
Solid Solution ◽  
Diffraction Study ◽  
Room Temperature ◽  
Fluorite Structure ◽  
Neutron Diffraction Study ◽  
Neutron Powder Diffraction ◽  
Face Centered Cubic ◽  
Aliovalent Substitution ◽  
Face Centered ◽  
The Ideal

It was seen during the phase relation studies on the CeO2–YO1.5 system that the ceria is able to accommodate a large anion deficiency caused by aliovalent substitution. A neutron powder diffraction study has been carried out at room temperature for the titled solid solution, Ce1−xYxO2−x/2 with x=0.32, which is an anion-deficient variant of the ideal fluorite structure. The structure has been found to be face centered cubic. No superlattice reflections have been observed indicating that the vacancies occupy the random positions in this highly defective solid solution. The bond distances and angles are also being reported.

Sign in / Sign up

Export Citation Format

Share Document