Effect of Mn Concentration on Magneto-mechnaical Properties in Directionally Solidified Ferromagnetic Shape Memory Ni-Mn-Ga Alloys

Heusler type alloys Ni50Mn25+xGa25-x (x=2,3,4 and 5) based on near stoichiometric Ni2MnGa compositions were directionally solidified using modified Bridgman method. The alloys thus prepared were characterized for their chemical composition, crystal structure, microstructure, phase transformation, magnetic and magneto-mechanical properties. The directionally solidified Ni50Mn30Ga20 alloy rod exhibited maximum magnetocrystalline value of 95 kJm-3 and lowest detwinning stresses for martensite phase of about 5MPa. The reversible room temperature magnetic field induced strain of 0.2% under external magnetic field of 0.6T and 0.05kN bias load was obtained for the directionally solidified Ni50Mn30Ga20 alloy.

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Mechanical properties of nickel beryllides

Journal of Materials Research ◽

10.1557/jmr.1989.1347 ◽

1989 ◽

Vol 4 (6) ◽

pp. 1347-1353 ◽

Cited By ~ 10

Author(s):

T. G. Nieh ◽

J. Wadsworth ◽

C. T. Liu

Keyword(s):

Crystal Structure ◽

Mechanical Properties ◽

Elastic Properties ◽

Room Temperature ◽

Vickers Microhardness ◽

Interstitial Oxygen ◽

Equiatomic Composition ◽

Room Temperature Ductility ◽

Hardness Increase ◽

Microhardness Tester

The elastic properties of nickel beryllide have been evaluated from room temperature to 1000 °C. The room temperature modulus is measured to be 186 GPa, which is relatively low by comparison with other B2 aluminides such as NiAl and CoAl. Hardness measurements were carried out on specimens that had compositions over the range from 49 to 54 at. % Be, using both a Vickers microhardness tester and a nanoindentor. It was found that the hardness of NiBe exhibits a minimum at the equiatomic composition. This behavior is similar to that of aluminides of the same crystal structure, e.g., NiAl and CoAl. The effect of interstitial oxygen on the hardness of NiBe has also been studied and the results show that the presence of oxygen in NiBe can cause a significant increase in hardness. It is demonstrated that the hardness increase for the off-stoichiometric compositions is primarily caused by interstitial oxygen and can only be attributed partially to anti-site defects generated in off-stoichiometric compositions. Nickel beryllides appear to have some intrinsic room temperature ductility, as evidenced by the absence of cracking near hardness indentations.

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Martensitic Transformation and Mechanical Properties of Fe-Doped Ni54Mn21Ga25 Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.687.500 ◽

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.

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Structure and Phase Stability of NiMnGa Ferromagnetic Shape Memory Alloys by Experimental and Ab Initio Techniques

Materials Science Forum ◽

10.4028/www.scientific.net/msf.638-642.2040 ◽

2010 ◽

Vol 638-642 ◽

pp. 2040-2045 ◽

Cited By ~ 1

Author(s):

Claude Esling ◽

Dao Yong Cong ◽

Jing Bai ◽

Yu Dong Zhang ◽

Jean Marc Raulot ◽

...

Keyword(s):

Crystal Structure ◽

Orientation Relationship ◽

Room Temperature ◽

Phenomenological Theory ◽

Shear Angle ◽

Martensitic Structure ◽

Ferromagnetic Shape Memory Alloys ◽

Austenite Grain ◽

Ferromagnetic Shape Memory ◽

Martensitic Variants

This paper summarizes some of our recent results on crystal structure, microstructure, orientation relationship between martensitic variants and crystallographic features of martensitic transformation in Ni-Mn-Ga FSMAs. It was shown that Ni53Mn25Ga22 has a tetragonal I4/mmm martensitic structure at room temperature. The neighboring martensitic variants in Ni53Mn25Ga22 have a compound twinning relationship with the twinning elements K1={112}, K2={11-2}, η1=<11-1>, η2=<111>, P={1-10} and s=0.379. The ratio of the relative amounts of twins within the same initial austenite grain is ~1.70. The main orientation relationship between austenite and martensite is Kurdjumov-Sachs (K-S) relationship. Based on the crystallographic phenomenological theory, the calculated habit plane is {0.690 -0.102 0.716}A (5.95° from {101}A), and the magnitude, direction and shear angle of the macroscopic transformation shear are 0.121, <-0.709 0.105 0.698>A (6.04° from <-101>A) and 6.88°, respectively.

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Analyses of Eutectoid Phase Transformations in Nb–SilicideIn SituComposites

Microscopy and Microanalysis ◽

10.1017/s1431927604040760 ◽

2004 ◽

Vol 10 (4) ◽

pp. 470-480 ◽

Cited By ~ 17

Author(s):

B.P. Bewlay ◽

S.D. Sitzman ◽

L.N. Brewer ◽

M.R. Jackson

Keyword(s):

Crystal Structure ◽

Phase Transformation ◽

High Temperature ◽

Room Temperature ◽

Bulk Composition ◽

High Strength ◽

Eutectoid Decomposition ◽

Quaternary Alloys ◽

Temperature Fracture

Nb–silicide in situ composites have great potential for high-temperature turbine applications. Nb–silicide composites consist of a ductile Nb-based solid solution together with high-strength silicides, such as Nb5Si3and Nb3Si. With the appropriate addition of alloying elements, such as Ti, Hf, Cr, and Al, it is possible to achieve a promising balance of room-temperature fracture toughness, high-temperature creep performance, and oxidation resistance. In Nb–silicide composites generated from metal-rich binary Nb-Si alloys, Nb3Si is unstable and experiences eutectoid decomposition to Nb and Nb5Si3. At high Ti concentrations, Nb3Si is stabilized to room temperature, and the eutectoid decomposition is suppressed. However, the effect of both Ti and Hf additions in quaternary alloys has not been investigated previously. The present article describes the discovery of a low-temperature eutectoid phase transformation during which (Nb)3Si decomposes into (Nb) and (Nb)5Si3, where the (Nb)5Si3possesses the hP16 crystal structure, as opposed to the tI32 crystal structure observed in binary Nb5Si3. The Ti and Hf concentrations were adjusted over the ranges of 21 to 33 (at.%) and 7.5 to 33 (at.%) to understand the effect of bulk composition on the phases present and the eutectoid phase transformation.

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ROOM TEMPERATURE MAGNETIC ANOMALIES IN BENZENE TREATED Bi–Pb–Sr–Ca–Cu–O POWDER

Modern Physics Letters B ◽

10.1142/s021798499100174x ◽

1991 ◽

Vol 05 (21) ◽

pp. 1447-1456 ◽

Cited By ~ 7

Author(s):

A. R. HARUTUNYAN ◽

L. S. GRIGORYAN ◽

A. S. KUZANYAN ◽

A. A. KUZNETSOV ◽

A. A. TERENTIEV ◽

...

Keyword(s):

Magnetic Field ◽

Chemical Composition ◽

Room Temperature ◽

Microprobe Analysis ◽

Magnetic Anomalies ◽

X Ray Diffraction ◽

X Ray ◽

Two Samples ◽

Field Dependent ◽

History Of

Two samples of benzene-treated Bi–Pb–Sr–Ca–Cu–O powder exhibited at 300 K magnetic field dependent diamagnetism and magnetization irreversibility. The treatment with benzene resulted also in the appearance of microwave absorption at low magnetic fields, while is sensitive to magnetic history of the sample. From X-ray diffraction data one can see that upon benzene treatment the reflections of 85 K and 110 K phases do not change practically, but a series of new reflections appeared, indicating a lattice modulation with 4.9 nm periodicity. A microprobe analysis revealed substantial inhomogeneity of chemical composition across the samples. The room temperature anomalies were weakened in one sample and vanished in the second upon thermal cycling.

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

Scanning ◽

10.1155/2017/4630156 ◽

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.

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

Materials Science Forum ◽

10.4028/www.scientific.net/msf.993.161 ◽

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.

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Atomic simulation of mechanical properties of irradiated iron

International Journal of Modern Physics C ◽

10.1142/s0129183120500278 ◽

2019 ◽

Vol 31 (02) ◽

pp. 2050027

Author(s):

Lei Ma ◽

Changsheng Li ◽

Ailong Zhang ◽

Wangyu Hu

Keyword(s):

Crystal Structure ◽

Mechanical Properties ◽

Molecular Dynamics ◽

Tensile Test ◽

Room Temperature ◽

Stacking Faults ◽

Dynamics Simulation ◽

Stress And Strain ◽

Micro Structure ◽

Atomic Simulation

The mechanical properties of irradiated iron are studied by molecular dynamics simulation. The initial models are irradiated with the energy of primary knocked-on atoms (PKA) of 10[Formula: see text]keV at 100, 300, 500 and 600 K, and then all the irradiated models are subjected to tensile test. The results reveal that the mechanical properties of irradiated iron are changed compared with un-irradiated iron, the yield stress and strain decrease after irradiation, and the irradiation causes the hardening of micro-structure at low temperature and high temperature, but it results in the softening of structure at room temperature. The plastic reduces for irradiated iron under tensile test, more stacking faults are formed in the crystal structure as the temperature increases.

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