STRUCTURAL CHANGES IN INVAR IRON-PALLADIUM ALLOYS BEFORE THE f.c.c.- b.c.t. MARTENSITIC TRANSFORMATION

1982 ◽  
Vol 43 (C4) ◽  
pp. C4-389-C4-394 ◽  
Author(s):  
M. Foos ◽  
C. Frantz ◽  
M. Gantois
Keyword(s):  
Martensitic Transformation ◽  
Structural Changes ◽  
Palladium Alloys ◽  
Iron Palladium

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.

Atomic Magnetic Moments in Dilute Iron—Palladium Alloys

1963 ◽  
Vol 34 (4) ◽  
pp. 1189-1190 ◽  
Author(s):  
J. W. Cable ◽  
E. O. Wollan ◽  
W. C. Koehler
Keyword(s):  
Magnetic Moments ◽  
Palladium Alloys ◽  
Iron Palladium

On the structural changes accompanying the fcc/hcp martensitic transformation in Fe–Mn–Co alloys

2002 ◽  
Vol 46 (11) ◽  
pp. 805-810 ◽  
Author(s):  
Pablo Marinelli ◽  
Marcos Sade ◽  
Armando Fernández Guillermet
Keyword(s):  
Martensitic Transformation ◽  
Structural Changes ◽  
Co Alloys

Phase Transitions and Elementary Processes in Shape Memory Alloys

2015 ◽  
Vol 1101 ◽  
pp. 124-128
Author(s):  
Osman Adiguzel
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Smart Materials ◽  
Structural Changes ◽  
Elementary Processes ◽  
Cooperative Movement ◽  
Β Phase

Shape memory effect is a peculiar property exhibited by certain alloy systems, and shape memory alloys are recognized to be smart materials. These alloys have important ability to recover the original shape of material after deformation, and they are used as shape memory elements in devices due to this property. The shape memory effect is facilitated by a displacive transformation known as martensitic transformation. Shape memory effect refers to the shape recovery of materials resulting from martensite to austenite transformation when heated above reverse transformation temperature after deforming in the martensitic phase. These alloys also cycle between two certain shapes with changing temperature.Martensitic transformations occur with cooperative movement of atoms by means of lattice invariant shears on a {110} - type plane of austenite matrix which is basal plane of martensite.Copper based alloys exhibit this property in metastable β-phase field. High temperature β-phase bcc-structures martensiticaly undergo the non-conventional structures following two ordered reactions on cooling, and structural changes in nanoscale level govern this transition cooling. Atomic movements are also confined to interatomic lengths due to the diffusionless character of martensitic transformation.

Martensitic Transformation, Structure and Magnetic Properties of Co-Ni-Ga Ferromagnetic Shape Memory Alloys

2007 ◽  
Vol 130 ◽  
pp. 141-146 ◽  
Author(s):  
B. Kostrubiec ◽  
Krystian Prusik ◽  
Ł. Madej ◽  
Henryk Morawiec
Keyword(s):  
Magnetic Properties ◽  
Martensitic Transformation ◽  
Structural Changes ◽  
Parent Phase ◽  
Martensite Phase ◽  
Ferromagnetic Shape Memory Alloys ◽  
Two Phase ◽  
Polycrystalline Alloys ◽  
Transformation Structure ◽  
Ferromagnetic Shape Memory

In the present paper the effect of heat treatment on microstructure, martensitic transformation temperatures and magnetic properties behavior of Co-Ni-Ga pollycrystal was discussed in detail. Microscopic observations revealed two types of two phase polycrystalline alloys: i) martensite with γ-precipitates and ii) parent phase with γ-precipitates. Making use of Xray and electron diffraction methods the crystal structure of martensite phase was identified as bct structure (with co/ao about 1.2). Annealing of Co-Ni-Ga alloy at 1223K/40 min causes a separation of martensitic and magnetic transformation and an increase of the Curie temperature by about 70K, after this annealing any significant structural changes in the parent (martensitic) and γ phase are not observed.

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