Mechanical twinning and subgrain formation in ordered Ti50Ni47Fe3

1988 ◽  
Vol 46 ◽  
pp. 618-619
Author(s):  
W. J. Moberly
Keyword(s):  
Mechanical Properties ◽  
Martensitic Transformation ◽  
Room Temperature ◽  
Cold Working ◽  
Thermomechanical Processing ◽  
Mechanical Twinning ◽  
Deformation Mechanisms ◽  
Tini Alloy ◽  
Recovery Annealing ◽  
Subgrain Formation

TiNi is an intermetallic compound with the B2(CsCl) crystal structure. As temperature decreases, it undergoes a martensitic transformation from cubic B2 to monoclinic B19', the reversibility of which is responsible for shape memory properties. Ordered intermetallics generally have limited ductilty, however, >50% elongation of TiNi has been produced by either warm or cold working. Consequently, thermomechanical processing has resulted in improved mechanical properties. TEM is required to characterize the deformation mechanisms (mechanical twinning and slip) and resulting substructures.Substitution of 3%Fe for Ni into the binary TiNi alloy (Ti50Ni47Fe3) depresses the martensitic transformation, such that room temperature working does not stress induce the martensitic transformation. In order to improve the mechanical properties of this B2 intermetallic, fully annealed (875°C/2 hrs) bars have been cold swaged 10%,20%,30% and 40%, followed by different recovery annealing treatments. Additional samples have been warm swaged at 500°C. The structure is observed optically and by TEM, utilizing Philips' EM 400 twin and EM 430 super twin microscopes.

Martensitic Transformation and Mechanical Properties of Fe-Doped Ni54Mn21Ga25 Alloys

2011 ◽  
Vol 687 ◽  
pp. 500-504
Author(s):  
S. X. Xue ◽  
S.S. Feng ◽  
P. Y. Cai ◽  
Q T Li ◽  
H. B. Wang
Keyword(s):  
Magnetic Field ◽  
Mechanical Properties ◽  
Magnetic Properties ◽  
Martensitic Transformation ◽  
Curie Temperature ◽  
Directional Solidification ◽  
Transformation Temperature ◽  
Room Temperature ◽  
Martensitic Transformation Temperature ◽  
Polycrystalline Alloys

Ni54Mn21-xFexGa25（x=0,1,3,5,7,9）polycrystalline alloys were prepared by the technique of directional solidification and the effect of substituting Fe for Mn on the martensitic transformation and mechanical properties of the alloys was analyzed. It was found that the Curie temperature increased with increasing substitution while the martensitic transformation temperature decreased. The Fe-doped Ni54Mn21Ga25 alloys exhibit excellent magnetic properties at room temperature; the typical Ni54Mn20Fe1Ga25 alloy shows a large magnetic-induced-strain of -1040 ppm at a magnetic field of 4000 Oe.

scholarly journals Nanoscale Mechanical Properties of Nanoindented Ni48.8Mn27.2Ga24 Ferromagnetic Shape Memory Thin Film

Scanning ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-5
Author(s):  
Xiaofei Fu ◽  
Chao Liu ◽  
Xili Lu ◽  
Xianli Li ◽  
Jingwei Lv ◽  
...  
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Martensitic Transformation ◽  
Magnetron Sputtering ◽  
Shape Memory ◽  
Room Temperature ◽  
Shape Recovery ◽  
Recovery Ratio ◽  
Dc Magnetron Sputtering ◽  
Ferromagnetic Shape Memory

The structure and nanoscale mechanical properties of Ni48.8Mn27.2Ga24 thin film fabricated by DC magnetron sputtering are investigated systematically. The thin film has the austenite state at room temperature with the L21 Hesuler structure. During nanoindentation, stress-induced martensitic transformation occurs on the nanoscale for the film annealed at 823 K for 1 hour and the shape recovery ratio is up to 85.3%. The associated mechanism is discussed.

Effect of Ca on Microstructure and Mechanical Properties of Directionally Solidified Mg-Zn-Ca Alloys

2020 ◽  
Vol 993 ◽  
pp. 161-165
Author(s):  
Yi Zhang ◽  
Xiao Hui Feng ◽  
Yuan Sheng Yang
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Tensile Tests ◽  
Deformation Mechanisms ◽  
Prismatic Slip ◽  
Directionally Solidified ◽  
Growth Orientation ◽  
Microstructure And Mechanical Properties ◽  
Dendritic Arm Spacing ◽  
Main Deformation

The effect of Ca on the microstructure and mechanical properties of directionally solidified (DSed) Mg-3Zn-xCa alloys (x=0.2,0.5,0.8wt.%) was investigated in the present work. The results showed that the DSed samples with the growth rate of 120 μm/s had columnar dendritic structures and the primary dendritic arm spacing (PDAS) decreased with the content of Ca increase. The TEM result indicated that the growth orientation of the DSed Mg-Zn-xCa alloys was , which was independent of the content of Ca. The tensile tests at room temperature showed that the mechanical properties of the DSed Mg-Zn-xCa alloys were strongly affected by the content of Ca. The addition of Ca remarkably improved the ultimate tensile strength (UTS) and the yield strength (YS), while dramatically reduced the elongation (El). Prismatic slip and twinning were the main deformation mechanisms in tensile tests.

Influence of Additions Sb on Mechanical Properties and Deformation Features of AZ31-Mg Alloy

2006 ◽  
Vol 15-17 ◽  
pp. 497-500
Author(s):  
Ling Wang ◽  
Su Gui Tian ◽  
Keun Yong Sohn ◽  
Kyung Hyun Kim
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Room Temperature ◽  
Az31 Alloy ◽  
Deformation Mechanisms ◽  
Az31 Mg Alloy ◽  
Deformation Features ◽  
Contrast Analysis ◽  
Observation Results

The mechanical properties and deformation features of AZ31-x%Sb alloys have been studied by means of the measurement of the ultimate tensile properties (UTS) and TEM observation. Results show that the UTS of AZ31 alloy is effectively enhanced to 297 MPa from 222 MPa, by additions of 0.84% Sb element, at room temperature, and the ultimate tensile strength of the alloy is still maintained up to 189MPa as temperature elevated to 200°C. Contrast analysis shows that the deformation mechanisms of AZ31-0.84%Sb alloy are twins and dislocations activated on basal and non-basal planes. The alloy displays the different deformation features at different deformation conditions.

scholarly journals Complex Structural Effects in Deformed High-Manganese Steel

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6935
Author(s):  
Joanna Kowalska ◽  
Janusz Ryś ◽  
Grzegorz Cempura
Keyword(s):  
Mechanical Properties ◽  
Phase Transformations ◽  
Mechanical Twinning ◽  
Carbon Steels ◽  
Deformation Mechanisms ◽  
Manganese Steel ◽  
Dislocation Slip ◽  
Chemical Compositions ◽  
High Manganese ◽  
Deformation Degree

The research presented in this paper is part of a larger project concerning deformation behavior, microstructure and mechanical properties of high-manganese steels with different chemical compositions and processed under various conditions. The current investigation deals with the development of microstructure and crystallographic texture of Fe-21.2Mn-2.73Al-2.99Si steel deformed in tension until fracture at ambient temperature. The deformation process of the examined steel turned out to be complex and included not only dislocation slip and twinning but also strain induced phase transformations (g ® e) and (g ® a′). The formation of e-martensite with hexagonal structure was observed within the microstructure of the steel starting from the range of lower strains. With increasing deformation degree, the a′-martensite showing a cubic structure gradually began to form. Attempts have been made to explain the circumstances or conditions for the occurrence of the deformation mechanisms mentioned above and their impact on the mechanical properties. The obtained results indicate that the strength and plastic properties of the steel substantially exceed those of plain carbon steels. Since both, mechanical twinning and the strain-induced phase transformations took place during deformation, it seems that both types of deformation mechanisms contributed to an increase in the mechanical properties of the examined manganese steel.

AEM Investigation of a Thermomechanically Processed U-6NB Alloy

1985 ◽  
Vol 43 ◽  
pp. 354-355
Author(s):  
Gail M. Ludtka
Keyword(s):  
Mechanical Properties ◽  
Solution Heat Treatment ◽  
Room Temperature ◽  
Thermomechanical Processing ◽  
High Yield ◽  
Ultrafine Grain ◽  
Superplastic Behavior ◽  
High Yield Strength ◽  
Ultrafine Grain Size ◽  
Before And After

The uranium-6 niobium (U-6Nb) alloy has been shown to exhibit elongations of 400-600% after a thermomechanical processing (TMP) sequence. This sequence (below the monotectoid temperature of 647°C) was utilized to develop the ultrafine grain size essential for superplastic behavior. The room temperature mechanical properties of the thermomechanically processed (TMP) U- 6Nb alloy before and after a gamma solution heat treatment (GSHT) were measured and compared to conventionally processed, GSHT U-6Nb alloy. These data are in Table I. The data show that the GSHT conditions have comparable mechanical properties and, so, the prior TMP treatment does not cause any loss of properties. However, the as-thermomechanically processed U-6Nb alloy exhibits negligible ductility and an extremely high yield strength. Metallography and AEM techniques have been utilized to characterize the TMP U- 6Nb microstructure to explain this behavior.

Processing-Property-Microstructure Relationships in Tial-Based Alloys

1996 ◽  
Vol 460 ◽  
Author(s):  
M H Loretto ◽  
D Hu ◽  
A Godfrey
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Creep Strength ◽  
Room Temperature ◽  
Thermomechanical Processing ◽  
Fracture Behaviour ◽  
Alloy Development ◽  
Processing Property ◽  
Optical And Electron Microscopy ◽  
Slip Transfer

ABSTRACTA range of TiAl-based alloys have been produced by plasma melting either small buttons (1kg samples) or ingots (up to 50kg). Some of the ingots have been atomised. The influence of thermomechanical processing on the microstructure of these materials has been assessed using optical and electron microscopy and the room temperature mechanical properties and creep strengths determined. It has been found that either through appropriate processing and/or through alloy development, it is possible to obtain alloys with room temperature strengths up to 1000MPa. Elongations of about 1% at room temperature have been obtained for alloys with this strength and this is coupled with significant improvements in creep strength over the reference alloy, Ti-48Al-2Mn-2Nb. The influence of the difficulty of slip transfer between gamma and alpha 2 has been assessed as one of the factors limiting ductility. Regions which are low in aluminium, which are present in the atomised powders initiate fracture at very low strains. These results are discussed in terms of the factors that control the strength and fracture behaviour of TiAl-based alloys.

Mechanical Properties and Microstructure of Certain Niaico(Hf) Alloys

1990 ◽  
Vol 186 ◽  
Author(s):  
S. M. Russell ◽  
C. C Law ◽  
L. S. Lin ◽  
G. W. Levan
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Martensitic Transformation ◽  
Low Temperatures ◽  
Creep Resistance ◽  
Room Temperature ◽  
Hexagonal Structure ◽  
High Temperature Strength ◽  
Room Temperature Ductility ◽  
Poor Creep Resistance

AbstractCobalt-modified NiAl alloys are being studied for their potential for room temperature ductility and toughness. An alloy of Ni - 29.3 a/o Al - 36.7 a/o Co has shown improved toughness and ductility with respect to binary NiAl alloys due in part to a stress-induced martensitic transformation. Furthermore, the cobalt additions have altered the slip behavior to {110}<111> type from {110} <001> for binary NiAl alloys. Hafnium was added to improve the alloy's relatively poor creep resistance and high temperature strength. Hf was found to be insoluble in the NiAlCo alloy and formed precipitates with a hexagonal structure. The Hfmodified alloy had improved high temperature strength. In addition, the Hf apparently changed the creep mechanism resulting in poorer creep resistance at low temperatures, but improved creep resistance at higher stresses and temperatures.

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