Transformation Behavior and Shape Memory Characteristics of Ti-45Ni-5Cu(at%) Alloy Ribbons Fabricated by Melt Spinning

2004 ◽  
Vol 449-452 ◽  
pp. 1093-1096 ◽  
Author(s):  
Tae Hyun Nam ◽  
Jae Hwa Lee ◽  
Tae Yeon Kim ◽  
Yeon Wook Kim
Keyword(s):  
Shape Memory ◽  
Melt Spinning ◽  
Constant Load ◽  
X Ray Diffraction ◽  
Transformation Behavior ◽  
X Ray ◽  
Density Of Dislocations ◽  
Large Lattice ◽  
One Step ◽  
Memory Characteristics

Transformation behaviors and shape memory characteristics of Ti-45Ni-5Cu alloy ribbons fabricated by melt spinning were investigated by means of optical microscopy, differential scanning calorimetries(DSC), X-ray diffraction and thermal cycling tests under constant load. They depended largely on temperatures of liquid metal. The B2-B19-B19’ two-step transformation occurred in the ribbons fabricated with the liquid whose temperature was higher than 1723 K, while the B2-B19’ one-step transformation occurred in the ribbons with the liquid at 1673 K. The stabilization of the B19 martensite in Ti-45Ni-5Cu alloy ribbons was ascribed to the high density of dislocations which made strong resistance to large lattice deformation associated with a formation of the B19’ martensite.

Shape Memory Characteristics of Ti50Ni50-xCux(x=35, 40) Alloy Strips

2008 ◽  
Vol 47-50 ◽  
pp. 463-466
Author(s):  
Yeon Wook Kim ◽  
Tae Hyun Nam ◽  
Sang Hoon Lee
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory ◽  
Alloy Strip ◽  
X Ray Diffraction ◽  
Strip Surface ◽  
X Ray ◽  
Columnar Grains ◽  
One Step ◽  
Transformation Hysteresis ◽  
Memory Characteristics

The shape memory alloy strips of Ti50Ni15Cu35 and Ti50Ni10Cu40 had been fabricated by arc melt overflow. Their microstructures and shape memory characteristics were investigated by means of X-ray diffraction, optical microscopy and differential scanning calorimetries. The microstructure of as-cast strips exhibited columnar grains normal to the strip surface. X-ray diffraction analysis showed that one-step martensitic transformation of B2-B19 occurred in the alloy strips. According to the DSC analysis, it was known that the martensitic transformation temperature (Ms) of B2→B19 was 71.2°C in Ti50Ni15Cu35 and 64.5°C in Ti50Ni10Cu40 alloy strip, respectively. During thermal cyclic deformation with the applied stress of 60 MPa, transformation hysteresis and elongation associated with the B2-B19 transformation were observed to be 4.9°C and 1.4% in Ti50Ni15Cu35 alloy strip. However, Ti50Ni10Cu40 alloy strip was so brittle that its mechanical properties could not be measured.

scholarly journals Nanocrystal, phase transformation and microstructure of Ni50Ti50 shape memory alloy

2018 ◽  
Vol 24 (02) ◽  
pp. 22-25
Author(s):  
Dovchinvanchig M ◽  
Chunwang Zhao
Keyword(s):  
Differential Scanning Calorimetry ◽  
Phase Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
One Step ◽  
Niti Matrix ◽  
Electronic Microscope

The nanocrystal, phase transformation and microstructure behavior of Ni50Ti50 shape memory alloy was investigated by scanning electronic microscope, X-ray diffraction and differential scanning calorimetry. The results showed that the microstructure of Ni-Ti binary alloy consists of the NiTi2 phase and the NiTi matrix phase. One-step phase transformation was observed alloy.

Mechanical Properties and Ordered Structure of Bacterial Poly(3-Hydroxybutyrate-Co-3-Hydroxyhexanoate) Fibers Stretched after Isothermal Crystallization near Tg

2011 ◽  
Vol 284-286 ◽  
pp. 1774-1777 ◽  
Author(s):  
Chang Kun Ding ◽  
Bo Wen Cheng ◽  
Qiong Wu
Keyword(s):  
Isothermal Crystallization ◽  
Melt Spinning ◽  
Room Temperature ◽  
Low Molecular Weight ◽  
Ordered Structure ◽  
X Ray Diffraction ◽  
Recombinant Bacteria ◽  
X Ray ◽  
Flexible Fibers ◽  
One Step

Biodegradable fibers of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) were prepared by melt spinning, followed by one-step-drawing with small crystal nuclei grown after isothermal crystallization near the glass transition temperature (Tg) and annealing at room temperature under tension. This new drawing technique is a very attractive method for obtaining flexible fibers from low-molecular-weight biopolyesters produced by recombinant bacteria. The ordered structure of PHBHHx fibers was investigated by tensile measurement, scanning electron microscopy, and wide-angle X-ray diffraction (WAXD). The tensile strength of 10 times one-step-drawn fiber after isothermal crystallization increased to 100 MPa. The WAXD profiles of PHBHHx fibers showed sharp reflections corresponding to highly oriented α-form (21helix conformation) crystal.

Hrem Studies of Rapidly Solidified Ni-Fe-Al-B Shape Memory Alloys.

1991 ◽  
Vol 246 ◽  
Author(s):  
R. Pērez ◽  
J. A. Juārez-Islas ◽  
P. Johansson ◽  
M. Wallin ◽  
S. J. Savage
Keyword(s):  
Shape Memory ◽  
Martensite Transformation ◽  
Melt Spinning ◽  
Image Contrast ◽  
X Ray Diffraction ◽  
Recoverable Strain ◽  
X Ray ◽  
Atomic Structures ◽  
Wide Range ◽  
Rapidly Solidified

AbstractA series of (NixFeyAlz)0.9983B0.0017 (where x=58-60, y=13-15 and z=26-28, in at%) alloys have been rapidly solidified by - melt spinning. The ribbons have been characterized by HREM, DSC, X-ray diffraction and recoverable strain measurements. The as-cast alloys exhibit excellent bend ductility (in contrast to B2 type alloys conventionally cast) and a wide range of transformation temperatures: Ms=244-466 K, Mf=200-395K, As=236-427K and Af=262-526K. X-ray diffraction shows the presence of β (NiAl), β′ (NiAl), γ (Ni3Al), γ′ (Ni3A1), Ni and other phases such as Fe3Al, FeAl, FeNi and Al5Fe2. It is the β- β′ diffusionless transformation which is responsible for the shape memory effect. The results obtained by transmission electron microscopy (TEM) show two different types of crystalline grains. In one case, the grains have a high density of twins which are the fingerprints of the martensite transformation. However, other areas in the specimen show crystalline grains with very poor image contrast due to the transformation from β′ -β. There are also sections in the specimens with domains of both crystalline sgrains in coexistance. Both crystalline grains have large amounts of precipitates. In the β′ (NiAl) phase the size of the precipitates range fron lnm to lOnm. In the γ (Ni3Al) phase large precipitates (20nm) can be found. Some of them display pentagonal shapes which resemble the image contrast obtained in the TEM for small icosahedral metallic particles. Experimental evidence is also obtained on different habit or twin planes. HREM images from the twinned areas suggest diferent kinds of atomic structures for the parent and martensite crystalline sections. These results give some insights into the nature of the martensite transformation.

X-Ray Diffraction Studies on Ti-Pd Shape Memory Alloys

2014 ◽  
Vol 783-786 ◽  
pp. 2517-2522
Author(s):  
Raju Arockiakumar ◽  
Madoka Takahashi ◽  
Satoshi Takahashi ◽  
Yoko Yamabe-Mitarai
Keyword(s):  
Phase Transformation ◽  
Shape Memory ◽  
Low Temperatures ◽  
Periodic Table ◽  
Room Temperature ◽  
Group Iv ◽  
X Ray Diffraction ◽  
Transformation Behavior ◽  
X Ray ◽  
B2 Phase

The phase transformation behavior of Ti-50Pd-5x (x =Zr, Hf, V, Nb, Ta, Cr, Mo, W) (at.%) alloys was studied by X-ray diffraction measurements from room temperature to 800 oC. In all the alloys, B19 martensite was observed at room temperature and it transformed to B2 phase upon heating. In addition, peaks corresponding to formation of (Ti, x)2Pd3 phase was seen for all the alloys. However, the temperature of formation of (Ti, x)2Pd3, interestingly, varied with respect to the elements group from the periodic table. Elements except from group IV (Zr and Hf) have been identified to accelerate the formation of (Ti, x)2Pd3 phase even at low temperatures (~400 oC).

Effect of Cooling Rate on the Transformation Temperatures of Ni50Ti36Hf14 Melt-Spun Ribbons

2018 ◽  
Vol 930 ◽  
pp. 345-348
Author(s):  
R.L. Soares ◽  
Walman Benicio Castro
Keyword(s):  
Differential Scanning Calorimetry ◽  
Martensitic Transformation ◽  
Cooling Rate ◽  
Melt Spinning ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Melt Spun ◽  
Melt Spun Ribbons ◽  
Memory Characteristics

Solidification structures and shape memory characteristics of Ni50Ti36Hf14(at.%) alloy ribbons prepared by melt spinning were investigated by means of differential scanning calorimetry and X-ray diffraction. In these experiments particular attention has been paid to change the velocity of cooling wheel from 20 to 40 m/s. Then the cooling rates of ribbons were controlled. The effect of this cooling rate on solidification structures and martensitic transformation behaviors is discussed. When the ribbon is produced at a wheel velocity of 40 m/s in melt spinning, the degree of supercooling becomes high because of its thinner thickness.

Microstructural Features and Shape-Memory Characteristics of Melt-Spun Ni-Al-Fe-B Ribbons

1991 ◽  
Vol 246 ◽  
Author(s):  
C. T. Liu ◽  
C. J. Sparks ◽  
J. A. Horton ◽  
E. P. George ◽  
C. A. Carmichael ◽  
...  
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Melt Spinning ◽  
Room Temperature ◽  
Alloy Composition ◽  
X Ray ◽  
Melt Spun ◽  
Bend Angles ◽  
Memory Characteristics

AbstractThis paper summarizes our recent study of NiAI+Fe+B alloy ribbons containing 4 to 20% Fe and doped with 300 wt ppm B. Alloy ribbons were successfully fabricated by rapid solidification via melt spinning. The alloys with 8% Fe and 34% Al-equivalent [=Al%+(Fe%)/2] showed the best bend ductility at room temperature. The ribbons exhibited a reversible martensite (body-centered orthorombic structure) to B2 transformation as evidenced by DSC, X-ray and TEM studies. The shape-memory effect, as characterized by measuring the recovery of bend angles with temperature, is sensitive to alloy composition, with the best recovery observed in SMA-15 (B-doped Ni-27% Al-14% Fe). Annealing at 600°C causes aging embrittlement; in particular, in alloys containing 12% Fe.

scholarly journals A Versatile Approach to Access Trimetallic Complexes Based on Trisphosphinite Ligands

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 593
Author(s):  
Juan Miranda-Pizarro ◽  
Macarena G. Alférez ◽  
M. Dolores Fernández-Martínez ◽  
Eleuterio Álvarez ◽  
Celia Maya ◽  
...  
Keyword(s):  
Coordination Chemistry ◽  
Late Transition Metal ◽  
X Ray Diffraction ◽  
X Ray ◽  
Full Characterization ◽  
Metal Precursors ◽  
Straightforward Method ◽  
One Step ◽  
Late Transition

A straightforward method for the preparation of trisphosphinite ligands in one step, using only commercially available reagents (1,1,1-tris(4-hydroxyphenyl)ethane and chlorophosphines) is described. We have made use of this approach to prepare a small family of four trisphosphinite ligands of formula [CH3C{(C6H4OR2)3], where R stands for Ph (1a), Xyl (1b, Xyl = 2,6-Me2-C6H3), iPr (1c), and Cy (1d). These polyfunctional phosphinites allowed us to investigate their coordination chemistry towards a range of late transition metal precursors. As such, we report here the isolation and full characterization of a number of Au(I), Ag(I), Cu(I), Ir(III), Rh(III) and Ru(II) homotrimetallic complexes, including the structural characterization by X-ray diffraction studies of six of these compounds. We have observed that the flexibility of these trisphosphinites enables a variety of conformations for the different trimetallic species.

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