Development of Fe-based shape memory alloys associated with face-centered cubic-hexagonal close-packed martensitic transformations: Part III. microstructures

1992 ◽  
Vol 23 (5) ◽  
pp. 1445-1454 ◽  
Author(s):  
J. H. Yang ◽  
C. M. Wayman
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Martensitic Transformations ◽  
Face Centered Cubic ◽  
Hexagonal Close Packed ◽  
Face Centered

Depletion of Manganese in the Surface Layers of Fe-Mn-Si Shape Memory Alloys by Annealing

2015 ◽  
Vol 363 ◽  
pp. 196-201
Author(s):  
Yusuke Onuki ◽  
Shun Fujieda ◽  
Kozo Shinoda ◽  
Hiroshi Ohtani ◽  
Tadakatsu Maruyama ◽  
...  
Keyword(s):  
Surface Layer ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Surface Layers ◽  
Hexagonal Close Packed ◽  
Compositional Changes ◽  
Face Centered ◽  
The Stability

X-ray diffraction (XRD) and electron microprobe microanalysis (EPMA) were used for characterizing the structure and composition of surface layers formed on austenitic Fe-Mn-Si shape memory alloys under vacuum. The XRD results demonstrated that during annealing, face centered cubic austenite is transformed to hexagonal close packed martensite on the alloy surface. The EMPA results revealed that manganese in the surface layer was depleted during annealing. Further, this analysis determined that the thickness of the surface layer of the alloy annealed at 1173 K for 1 h was approximately 20 μm and that value is consistent with the depth detected by XRD. The compositional changes of the surface layers such as manganese depletion by annealing were discussed based on the ternary Fe-Mn-Si phase diagram. Although the formation of body centered cubic ferrite is detrimental to shape memory alloys, the amount of manganese was also observed to change during processing and strongly influence the stability of the shape memory alloys.

scholarly journals Magnetic Properties of Nickel-Titanium Alloy during Martensitic Transformations under Plastic and Elastic Deformation

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 665
Author(s):  
Ludmila I. Kveglis ◽  
Fedor M. Noskov ◽  
Mikhail N. Volochaev ◽  
Alexander V. Nyavro ◽  
Aleksander Filarowski
Keyword(s):  
Titanium Nickelide ◽  
Tensile Deformation ◽  
Intermediate Phase ◽  
Martensitic Transformations ◽  
Face Centered Cubic ◽  
Hexagonal Close Packed ◽  
Bcc Lattice ◽  
Fcc Lattice ◽  
Face Centered ◽  
B2 Structure

This paper focuses on the processes of the occurrence of magnetization during structure formation in samples of Ni51Ti49 alloy under deformation conditions. The possibility of the existence of a phase with an FCC (face-centered cubic) lattice in titanium nickelide has been demonstrated by electron microscopy and electron diffraction. It has been discovered that the interplanar distances of BCC110 (body-centered cubic), FCC111, and HCP002 (hexagonal close packed) in the alloy under study have similar values, which indicates the possibility of their mutual polymorphic transformation. Based on the modular self-organization, a scheme of martensitic transformations in titanium nickelide from the B2 structure (BCC lattice) to the B19’ structure (HCP lattice) through an intermediate phase with an FCC lattice is proposed. It is shown that lenticular crystals appear in the Ni51Ti49 alloy under tensile deformation until rupture, which is accompanied by the onset of ferromagnetism. The effect of magnetization in Ni51Ti49 samples when immersed in liquid nitrogen has been also discovered. In this case, the reason for the appearance and disappearance of magnetization can be associated with microdeformation processes caused by direct and reverse martensitic transitions that occur during cooling and heating of the samples.

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.

scholarly journals Stability and equation of state of face-centered cubic and hexagonal close packed phases of argon under pressure

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Agnès Dewaele ◽  
Angelika D. Rosa ◽  
Nicolas Guignot ◽  
Denis Andrault ◽  
João Elias F. S. Rodrigues ◽  
...  
Keyword(s):  
Equation Of State ◽  
Single Crystal ◽  
Single Crystal Sample ◽  
Moderate Pressure ◽  
Face Centered Cubic ◽  
Experimental Conditions ◽  
Crystal Sample ◽  
Hexagonal Close Packed ◽  
Face Centered ◽  
Fcc Phase

AbstractThe compression of argon is measured between 10 K and 296 K up to 20 GPa and and up to 114 GPa at 296 K in diamond anvil cells. Three samples conditioning are used: (1) single crystal sample directly compressed between the anvils, (2) powder sample directly compressed between the anvils, (3) single crystal sample compressed in a pressure medium. A partial transformation of the face-centered cubic (fcc) phase to a hexagonal close-packed (hcp) structure is observed above 4.2–13 GPa. Hcp phase forms through stacking faults in fcc-Ar and its amount depends on pressurizing conditions and starting fcc-Ar microstructure. The quasi-hydrostatic equation of state of the fcc phase is well described by a quasi-harmonic Mie–Grüneisen–Debye formalism, with the following 0 K parameters for Rydberg-Vinet equation: $$V_0$$ V 0 = 38.0 Å$$^3$$ 3 /at, $$K_0$$ K 0 = 2.65 GPa, $$K'_0$$ K 0 ′ = 7.423. Under the current experimental conditions, non-hydrostaticity affects measured P–V points mostly at moderate pressure ($$\le$$ ≤ 20 GPa).

scholarly journals Microstructure Refinement by Low-Temperature Ausforming in an Fe-Based Metastable High-Entropy Alloy

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 742
Author(s):  
Motomichi Koyama ◽  
Takeaki Gondo ◽  
Kaneaki Tsuzaki
Keyword(s):  
Low Temperature ◽  
Plastic Anisotropy ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Microstructure Refinement ◽  
Hexagonal Close Packed ◽  
Solution Treated Condition ◽  
Solution Treated ◽  
Face Centered

The effects of ausforming in an Fe30Mn10Cr10Co high-entropy alloy on the microstructure, hardness, and plastic anisotropy were investigated. The alloy showed a dual-phase microstructure consisting of face-centered cubic (FCC) austenite and hexagonal close-packed (HCP) martensite in the as-solution-treated condition, and the finish temperature for the reverse transformation was below 200 °C. Therefore, low-temperature ausforming at 200 °C was achieved, which resulted in microstructure refinement and significantly increased the hardness. Furthermore, plasticity anisotropy, a common problem in HCP structures, was suppressed by the ausforming treatment. This, in turn, reduced the scatter of the hardness.

Observation of the Formation Processes of Hexagonal Close-packed and Face-centered Cubic Ru Nanoparticles

2019 ◽  
Vol 48 (9) ◽  
pp. 1062-1064 ◽  
Author(s):  
Naoki Araki ◽  
Kohei Kusada ◽  
Satoru Yoshioka ◽  
Takeharu Sugiyama ◽  
Toshiaki Ina ◽  
...  
Keyword(s):  
Face Centered Cubic ◽  
Formation Processes ◽  
Hexagonal Close Packed ◽  
Ru Nanoparticles ◽  
Face Centered

Stars and stripes. Nanoscale misfit dislocation patterns on surfaces

2002 ◽  
Vol 74 (9) ◽  
pp. 1663-1671 ◽  
Author(s):  
Raghani Pushpa ◽  
Shobhana Narasimhan
Keyword(s):  
Surface Structure ◽  
Misfit Dislocation ◽  
Domain Walls ◽  
Chemical Potential ◽  
Model System ◽  
Misfit Dislocations ◽  
Face Centered Cubic ◽  
Hexagonal Close Packed ◽  
Structure Changes ◽  
Face Centered

Close-packed metal surfaces and heteroepitaxial systems frequently display a structure consisting of regularly spaced misfit dislocations, with a network of domain walls separating face-centered cubic (fcc) and hexagonal close-packed (hcp) domains. These structures can serve as templates for growing regularly spaced arrays of nanoislands. We present a theoretical investigation of the factors controlling the size and shape of the domains, using Pt(111) as a model system. Upon varying the chemical potential, the surface structure changes from being unreconstructed to the honeycomb, wavy triangles, "bright stars", or Moiré patterns observed experimentally on Pt(111) and other systems. For the particular case of Pt(111), isotropically contracted star-like patterns are favored over uniaxially contracted stripes.

Sign in / Sign up

Export Citation Format

Share Document