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 Study of Amorphous NixZr(100-x)-Alloys Prepared by Melt-Spinning

1991 ◽  
Vol 46 (11) ◽  
pp. 947-950
Author(s):  
W.-M. Kuschke ◽  
P. Lamparter ◽  
S. Steeb
Keyword(s):  
Melt Spinning ◽  
Pair Correlation ◽  
Nickel Concentration ◽  
Superconducting Transition ◽  
X Ray Diffraction ◽  
X Ray ◽  
Coordination Numbers ◽  
Structure Factors ◽  
Wide Range ◽  
Good Agreement

AbstractAmorphous Ni-Zr-alloys can be prepared by melt-spinning within a wide range of composition. Studies by X-ray diffraction yielded structure factors, pair correlation functions, total coordination numbers and atomic distances in dependence on the nickel concentration in the range of 25 up to 45 atomic percent. The change of the total coordination number and atomic distances turned out to be linear with the composition in this range. This is in good agreement with the linear composition dependence of the superconducting transition temperature, magnetic susceptibility, crystallization temperature, and electrical resistivity in the investigated range of composition.

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.

scholarly journals Redetermination of the first unknown protein MicroED structure by high resolution X-ray diffraction

2021 ◽  
Author(s):  
Hongyi Xu ◽  
Xiaodong Zou ◽  
Martin Högbom ◽  
Hugo Lebrette
Keyword(s):  
Protein Structures ◽  
Real Life ◽  
Relevant Information ◽  
Binding Pocket ◽  
X Ray Diffraction ◽  
X Ray ◽  
Biologically Relevant ◽  
Atomic Structures ◽  
Unknown Protein ◽  
Wide Range

Microcrystal electron diffraction (MicroED) has the potential to considerably impact the field of structural biology. Indeed, the method can solve atomic structures of a wide range of molecules, beyond the reach of single particle cryo-electron microscopy, exploiting crystals too small for X-ray diffraction (XRD) even using X-ray free-electron lasers. However, until the first unknown protein structure – a R2-like ligand binding oxidase from Sulfolobus acidocaldarius (SaR2lox) – was recently solved at 3.0 Å resolution, MicroED had only been used to study known protein structures previously obtained by XRD. Here, after adapting sample preparation protocols, the structure of the SaR2lox protein originally solved by MicroED was redetermined by XRD at 2.1 Å resolution. In light of the higher resolution XRD data and taking into account experimental differences of the methods, the quality of the MicroED structure is examined. The analysis demonstrates that MicroED provided an overall accurate model, revealing biologically relevant information specific to SaR2lox, such as the absence of an ether cross-link, but did not allow to detect the presence of a ligand visible by XRD in the protein binding pocket. Furthermore, strengths and weaknesses of MicroED compared to XRD are discussed in the perspective of this real-life protein example. The study provides fundaments to help MicroED become a method of choice for solving novel protein structures.

INFLUENCE OF POROSITY ON SHAPE MEMORY BEHAVIOR OF POROUS TiNi SHAPE MEMORY ALLOY

2008 ◽  
Vol 01 (03) ◽  
pp. 215-219 ◽  
Author(s):  
JIANYU XIONG ◽  
YUNCANG LI ◽  
PETER D. HODGSON ◽  
CUI'E WEN
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Tini Alloy ◽  
Compression Tests ◽  
X Ray Diffraction ◽  
Recoverable Strain ◽  
Strain Concentration ◽  
X Ray ◽  
Shape Memory Behavior ◽  
Porous Ti

Porous Ti -50.5at.% Ni shape memory alloy (SMA) samples with a range of porosities were prepared by spacer sintering. The porous structure of the alloy was examined using scanning electron microscopy (SEM). The phase constituents of the porous TiNi alloy were determined by X-ray diffraction (XRD). The shape memory behavior of the porous TiNi alloy was investigated using loading–unloading compression tests. Results indicate that the porous TiNi alloy exhibits superelasticity and the recoverable strain by the superelasticity decreases with the increase of porosity. After a prestrain of 7%, the superelastically recovered strains for the porous TiNi alloy samples with porosities of 46%, 59%, 69% and 77% are 2.0%, 1.8%, 1.5% and 1.3%, respectively. The pores in the TiNi alloy samples cause stress/strain concentration, as well as crack initiation, which adversely affect the shape memory behavior of the porous TiNi alloy.

Rapid Solidification Microstructures and Precipitation in AL-Mn Alloys

1983 ◽  
Vol 28 ◽  
Author(s):  
R. J. Schaefer ◽  
D. Shechtman ◽  
F. S. Biancaniello
Keyword(s):  
Rapid Solidification ◽  
Growth Kinetics ◽  
Melt Spinning ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rapidly Solidified ◽  
Solidification Microstructures ◽  
Al Matrix

ABSTRACTRapidly solidified Al containing up to to 15 wt.% Mn was prepared by melt spinning. The alloys were examined by TEM and X-ray diffraction in the as-spun condition and after annealing at 450°C. Four precipitate phases were detected, and their growth kinetics were correlated to subgrain structures in the Al matrix.

A microstructural characterization of Co-Zr type permanent-magnet materials

1991 ◽  
Vol 49 ◽  
pp. 782-783
Author(s):  
K. R. Lawless ◽  
G. C. Hadjipanayis
Keyword(s):  
Melt Spinning ◽  
Microstructural Characterization ◽  
X Ray Diffraction ◽  
Ion Milling ◽  
X Ray ◽  
Heat Treated ◽  
Diffraction Patterns ◽  
Rapidly Solidified ◽  
Hard Magnetic Properties

Considerable interest has been shown recently in the hard magnetic properties of Co-Zr, Co-Zr-B, and Co-Hf-B alloys, but as yet no detailed microstructural studies have been published. The Co-Zr phase diagram seems to be reasonably well known, although the crystal structure of the Co11Zr2 phase is only partially determined. This paper will report on some preliminary studies of rapidly solidified Co-Zr-B-Si and Co-Hf-B-Si alloys and binary Co-Zr alloys.All specimens used in this study were prepared by melt spinning. Specific alloys were heat treated at temperatures from 650 to 900°C. TEM specimens were prepared from ribbon material by ion milling.X-ray diffraction studies of these alloys all showed a characteristic broad peak centered around d = 0.205nm. Although it was obvious that this was a complex peak, attempts to deconvolute it were unsuccessful. SAD patterns revealed that major phases in the alloys were very heavily faulted, thus giving rise to the very confusing X-ray diffraction patterns.

Microstructural analysis for Sn-Bi-Sb-In alloy prepared by rapid solidification

2016 ◽  
Vol 12 (2) ◽  
pp. 4244-4254
Author(s):  
Sara Mosaad Mahlab ◽  
Mustafa Kamal ◽  
Abd El-Raouf Mansour
Keyword(s):  
Electron Microscopy ◽  
Microstructure Evolution ◽  
Melt Spinning ◽  
Vickers Microhardness ◽  
Microstructural Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rapidly Solidified ◽  
Melt Spinning Technique ◽  
Scanning Electron

In the present study, Sn70-X at.% -Bi15 at.% -Sb15 at.%- Inx at.%  alloy ( x= 0, 2, 4, 6),  were prepared by melt spinning technique. Optical microscopy, scanning electron microscopy combined with energy dispersive X-ray analysis (SEM-EDX), X-ray diffraction analysis (XRD), and Vickers microhardness (Hv); were used to characterize the phase transformation and the microstructure evolution. The results contribute to the understanding of the microstructure evolution in alloys of the type prepared by melt spinning technique. This work reports on a comparative study of the rapidly solidified, in order to compare the microhardness and microstructural analysis. 

Mechanical Properties of Ordered Fe-Al-X Alloys

1990 ◽  
Vol 213 ◽  
Author(s):  
Ujjwal Prakash ◽  
Robert A. Buckley ◽  
Howard Jones
Keyword(s):  
Electron Microscopy ◽  
Melt Spinning ◽  
Composition Range ◽  
Tensile Fracture ◽  
Strengthening Mechanisms ◽  
X Ray Diffraction ◽  
X Ray ◽  
Al Content ◽  
Heat Treated ◽  
Rapidly Solidified

ABSTRACTFe-Al-X alloys (X = Cr, Mo) in the composition range 50 to 80 at. % Fe, 0 to 20 at. % X were rapidly solidified by chill-block melt-spinning. As-spun and heat treated ribbons were characterised by optical and electron microscopy and X-ray diffraction. Strengthening mechanisms were identified using microhardness measurements. Tensile fracture surfaces of ribbons reveal ductile to cleavage to intergranular fracture transitions with increasing Al-content. An increasing preponderance of cleavage fracture with increasing ternary substitution for Fe was observed.

Microstructures of Fe-Pd Alloy Ribbons Subjected to Rapidly Solidified Melt Spinning

2013 ◽  
Vol 738-739 ◽  
pp. 431-435
Author(s):  
Yoichi Kishi ◽  
Takeshi Kubota ◽  
Zenjiro Yajima ◽  
Teiko Okazaki ◽  
Yasubumi Furuya ◽  
...  
Keyword(s):  
Pole Figure ◽  
Melt Spinning ◽  
Room Temperature ◽  
Parent Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Oriented Texture ◽  
Pd Alloy ◽  
Rapidly Solidified

Microstructures of the Fe-29.6at%Pd alloy ribbons were observed with an X-ray diffractometer and a transmission electron microscope. The X-ray diffraction profiles at room temperature showed that the ribbon consists of FCT martensitic phase and FCC parent phase. Moreover, the ribbon exhibits a strongly 200-oriented texture analyzing with pole figure measurements. TEM bright field images for the cross section of the ribbon showed high-density striation in the FCT martensite variants. Twin-related two sets of reflections were observed in the SAED patterns taken of the FCT martensite variants. FCT was nearly parallel to the thickness direction according to the analysis of the SAED patterns. This result corresponds to the pole figure measurements.

Logarithmic Relaxation of Resistance in Time of Annealed and Plastically Deformed Au80Fe20

2000 ◽  
Vol 634 ◽  
Author(s):  
P. Allia ◽  
M. Baricco ◽  
E. Bosco ◽  
M. Coisson ◽  
D. Falletti ◽  
...  
Keyword(s):  
Electrical Resistance ◽  
Melt Spinning ◽  
Magnetic Measurements ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Thermal Treatments ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Rapidly Solidified

ABSTRACTRapidly solidified Au80Fe20 ribbons were prepared either by melt spinning or by solidstate quenching of a homogenised master alloy. The as-quenched sample displays a paramagnetic behavior indicating a perfect solid solution of Fe in the Au matrix. Subsequent anneals have been performed to induce the precipitation of Fe particles. X-ray diffraction technique have been exploited to determine the alloy microstructure. The structural stability have been studied by measuring electrical properties in isothermal and tempering condition. The variation of magnetisation and electrical resistance have been measured after submitting the samples to plastic deformation. A logarithmic relaxation of the electrical resistance is observed in all studied samples after deformation. Magnetic hysteresis loops have been measured in as-quenched and annealed samples at different temperatures. X-ray diffraction and magnetic measurements indicate that thermal treatments have been successful in inducing the precipitation of both bcc and fcc Fe clusters.

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