Investigations On In Situ Nanocrystallization And Magnetic Properties For Amorphous Fe78Si9B13 Ribbons

1999 ◽  
Vol 577 ◽  
Author(s):  
Xiangeheng Sun ◽  
A. Cabral-Prieto ◽  
M. Jose Yacaman ◽  
Wensheng Sun
Keyword(s):  
Amorphous Phase ◽  
Amorphous State ◽  
Field Pattern ◽  
Transmission Electron ◽  
Measurement Results ◽  
Optimum Annealing Temperature ◽  
Increasing Temperature ◽  
Differential Scanning Calorimeters ◽  
Nanocrystalline Phases

ABSTRACTThe amorphous state of ferromagnetic Fe78Si9B13 (Metglas 2605S-2) and its nanocrystallization were investigated by in situ transmission electron microscope (TEM), Xray diffraction (XRD), Mossbauer spectroscopy (MS), differential scanning calorimeters (DSC) and magnetic moment measurements. The Mössbauer spectrum exhibited an essentially symmetric hyperfine field pattern of 259KOe in as-quenched amorphous state at room temperature. The Curie and crystallization temperature were determined to be Tc=708K and Tx= 803K, respectively. The Tx value was in good agreement with DSC measurement results. The occupied fraction of the nanocrystalline phases of α-Fe(Si) and Fe2B at in situ optimum annealing temperature was about 57% and 43%, respectively. It is notable that the magnetization of the amorphous phase decreases more rapidly with increasing temperature than those of nanocrystalline ferromagnetism, suggesting the presence of the distribution of exchange interaction in the amorphous phase or high metalloid contents.

Investigations on in situ Nanocrystallization and Magnetic Properties for Amorphous Fe78Si9B13 Ribbons

1999 ◽  
Vol 562 ◽  
Author(s):  
Xiangcheng Sun ◽  
A. Cabral-Prieto ◽  
M. Jose Yacaman ◽  
Wensheng Sun
Keyword(s):  
Amorphous Phase ◽  
Annealing Temperature ◽  
Amorphous State ◽  
Field Pattern ◽  
Transmission Electron ◽  
Optimum Annealing Temperature ◽  
Differential Scanning Calorimeters ◽  
Nanocrystalline Phases ◽  
Good Agreement

ABSTRACTThe amorphous state of ferromagnetic Fe78Si9B13 (Metglas 2605S-2) and itsnanocrystallization were investigated by in situ transmission electron microscope (TEM), Xraydiffraction (XRD), Mossbauer spectroscopy (MS), differential scanning calorimeters(DSC) and magnetic moment measurements. The Mössbauer spectrum exhibited anessentially symmetric hyperfine field pattern of 259KOe in as-quenched amorphous state atroom temperature. The Curie and crystallization temperature were determined to beTc=708K and Tx.= 803K, respectively. The Tx value was in good agreement with DSCmeasurement results. The occupied fraction of the nanocrystalline phases of α-Fe(Si) andFe2 at in situ optimum annealing temperature was about 57% and 43%, respectively. It isnotable that the magnetization of the amorphous phase decreases more rapidly withincreasing temperature than those of nanocrystalline ferromagnetism, suggesting thepresence of the distribution of exchange interaction in the amorphous phase or highmetalloid contents.

Ferromagnetic properties and Nanocrystallization behavior of Amorphous (Fe0.99Mo0.01)78Si9B13 Ribbons

2001 ◽  
Vol 674 ◽  
Author(s):  
Xiang-Cheng Sun ◽  
J. A. Toledo ◽  
S. Galindo ◽  
W. S. Sun
Keyword(s):  
Amorphous Phase ◽  
Magnetic Ordering ◽  
Metastable Phases ◽  
X Ray Diffraction ◽  
Ferromagnetic Properties ◽  
X Ray ◽  
Diffraction Patterns ◽  
Optimum Annealing Temperature ◽  
Increasing Temperature ◽  
Differential Scanning Calorimeters

ABSTRACTFerromagnetic properties and nanocrystallization process of soft ferromagnetic (Fe0.99Mo0.01)78Si9B13 ribbons are studied by transmission electron microscope (TEM), X-ray diffraction (XRD), Mössbauer spectroscopy (MS), differential scanning calorimeters (DSC) and magnetization measurements. The Curie and crystallization temperature are determined to be TC=665K and Tx = 750K, respectively. The Tx value is in well agreement with DSC measurement results. X-ray diffraction patterns had shown a good reconfirm of two metastable phases (Fe23B6, Fe3B) were formed under in-situ nanocrystallization process. Of which these metastable phases embedded in the amorphous matrix have a significant effect on magnetic ordering. The ultimate nanocrystalline phases of α-Fe (Mo, Si) and Fe2B at optimum annealing temperature had been observed respectively. It is notable that the magnetization of the amorphous phase decreases more rapidly with increasing temperature than those of nanocrystalline ferromagnetism, suggesting the presence of the distribution of exchange interaction in the amorphous phase or high metalloid contents.

Role of boundaries in the crystallization of amorphous films

1988 ◽  
Vol 46 ◽  
pp. 626-627
Author(s):  
D. A. Smith
Keyword(s):  
Low Temperature ◽  
Amorphous State ◽  
Nucleation And Growth ◽  
Amorphous Films ◽  
Island Nucleation ◽  
Surface Steps ◽  
Transmission Electron ◽  
Component Systems ◽  
Temperature Deposition

The nucleation and growth processes which lead to the formation of a thin film are particularly amenable to investigation by transmission electron microscopy either in situ or subsequent to deposition. In situ studies have enabled the observation of island nucleation and growth, together with addition of atoms to surface steps. This paper is concerned with post-deposition crystallization of amorphous alloys. It will be argued that the processes occurring during low temperature deposition of one component systems are related but the evidence is mainly indirect. Amorphous films result when the deposition conditions such as low temperature or the presence of impurities (intentional or unintentional) preclude the atomic mobility necessary for crystallization. Representative examples of this behavior are CVD silicon grown below about 670°C, metalloids, such as antimony deposited at room temperature, binary alloys or compounds such as Cu-Ag or Cr O2, respectively. Elemental metals are not stable in the amorphous state.

In situ transmission electron microscope measurements of solid Al-solid Pb and solid Al-liquid Pb surface-energy anisotropy in rapidly solidified Al-5% Pb (by mass)

1987 ◽  
Vol 414 (1847) ◽  
pp. 499-507 ◽  
Keyword(s):  
Electron Microscope ◽  
Melting Point ◽  
Surface Energy ◽  
Transmission Electron Microscope ◽  
Room Temperature ◽  
Transmission Electron ◽  
Increasing Temperature ◽  
Rapidly Solidified ◽  
Al Matrix

Alloys of Al-5% Pb and Al-5% Pb-0.5% Si (by mass) have been manufactured by rapid solidification and then examined by transmission electron microscopy. The rapidly solidified alloy microstructures consist of 5-60 nm Pb particles embedded in an Al matrix. The Pb particles have a cube-cube orientation relation with the Al matrix, and are cub-octahedral in shape, bounded by {100} Al, Pb and {111} Al, Pb facets. The equilibrium Pb particle shape and therefore the anisotropy of solid Al-solid Pb and solid Al-liquid Pb surface energies have been monitored by in situ heating in the transmission electron microscope over the temperature range between room temperature and 550°C. The ani­sotropy of solid Al-solid Pb surface energy is constant between room temperature and the Pb melting point, with a {100} Al, Pb surface energy about 14% greater than the {111} Al, Pb surface energy, in good agreement with geometric near-neighbour bond energy calculations. The {100} AI, Pb facet disappears when the Pb particles melt, and the anisotropy of solid Al-liquid Pb surface energy decreases gradually with increasing temperature above the Pb melting point, until the Pb particles become spherical at about 550°C.

A transmission electron microscopy investigation of inverse melting in Nb45Cr55

1997 ◽  
Vol 12 (7) ◽  
pp. 1872-1884 ◽  
Author(s):  
W. Sinkler ◽  
C. Michaelsen ◽  
R. Bormann
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Amorphous Phase ◽  
Amorphous State ◽  
Transmission Electron ◽  
Microscopy Investigation ◽  
Electron Microscopy Investigation ◽  
Medium Range ◽  
High Resolution Tem ◽  
And Calorimetry

In inverse melting, a supersaturated crystalline phase transforms polymorphously under heat treatment to the amorphous state. Inverse melting of body-centered cubic (bcc) Nb45Cr55 is studied using transmission electron microscopy (TEM) and high resolution TEM (HRTEM). The crystalline to amorphous transformation is heterogeneous, initiating at the bcc grain boundaries. HRTEM reveals 2–3 nm domains with medium range order (MRO) in the amorphous phase. Preferred orientation of MRO domains is found on a scale corresponding to the precursor bcc grain size. Using HRTEM and calorimetry, MRO development in cosputtered Nb45Cr55 films is characterized and compared to that in the amorphous phase produced by inverse melting.

Formation and Crystallization of Amorphous Silicides at the Interface Between Thin Metal and Amorphous Silicon Films

1982 ◽  
Vol 18 ◽  
Author(s):  
S. R. Herd ◽  
K. Y. Ahn ◽  
K. N. Tu
Keyword(s):  
Amorphous Silicon ◽  
Amorphous Phase ◽  
Crystalline Silicon ◽  
Silicon Layer ◽  
Diffraction Peak ◽  
Gold Films ◽  
Cubic Form ◽  
No Formation ◽  
Transmission Electron

We investigated the interaction of extremely thin (less than 10 nm) crystalline gold and rhodium films with amorphous silicon by transmission electron microscope in situ annealing. In thin Au/Si bilayers an amorphous phase with a diffraction peak at d ≂ 0.226 nm is formed by thermal annealing between 150 and 200 °C. Depending on the thickness and composition, silicon sputtered onto thin gold films leads to the formation of a layer of amorphous silicon and a partially amorphous Au-Si layer during deposition. The silicon layer crystallizes by itself at temperatures as low as 150 °C, and at 300 °C the amorphous Au–Si layer crystallizes into a metastable gold silicide (for silicon-rich compositions). In Rh/Si bilayers an amorphous Rh–Si phase is formed by annealing to 300 °C and can be detected by electron diffraction for a rhodium thickness of less than 5 nm and compositions with more than 50% Si if completely reacted. Above 300 °C the amorphous Rh-Si crystallizes preferentially in the cubic form of RhSi for intermediate silicon compositions and in the orthorhombic form of RhSi for high silicon compositions. Excess amorphous silicon is not found to have a lowered crystallization temperature when in contact with the amorphous Rh-Si alloy, and crystalline silicon is only observed above 730 °C together with the cubic and/or orthorhombic RhSi. In Rh/Si bilayers with a thicker rhodium layer, no formation of an amorphous phase was observed on annealing; instead crystalline Rh2Si forms during annealing above 300 °C.

Temperature-Dependent Magnetic Properties of SiO2-Coated Ni75Fe25 Nanoparticles

2002 ◽  
Vol 755 ◽  
Author(s):  
Mingzhong Wu ◽  
Y.D. Zhang ◽  
S. Hui ◽  
Shihui Ge
Keyword(s):  
Magnetic Properties ◽  
Calcination Temperature ◽  
Quantum Interference ◽  
Amorphous State ◽  
Ferromagnetic State ◽  
Oxide Content ◽  
Temperature Dependent ◽  
Bloch Constant ◽  
Transmission Electron ◽  
Increasing Temperature

ABSTRACTSiO2-coated Ni75Fe25 nanoparticles were prepared using a wet chemical method and their structure and magnetic properties were investigated using x-ray diffraction, high-resolution transmission electron microscopy, and a superconducting quantum interference device magnetometer. The SiO2 material was in an amorphous state. The Ni75Fe25 nanoparticles were in a simple cubic state and contained inner oxide (Ni-oxide and Fe-oxide) cores whose size decreased with increasing calcination temperature. The nanoparticles were basically in the ferromagnetic state. Their saturation magnetization increased with increasing calcination temperature, whereas their coercivity decreased with increasing calcination temperature. The nanoparticles exhibited strong temperature-dependent magnetic behaviors. The Bloch exponent fell from 1.5 for the bulk to smaller values and decreased with increasing oxide content, while the Bloch constant was much bigger than that for bulk and increased significantly with oxide content. The value of coercivity decreased with increasing temperature, and this decrease was more pronounced for the nanoparticles containing high oxide content. The exchange anisotropy arising from the exchange coupling across the Ni75Fe25/oxide interfaces was examined and was used to interpret the observed temperature-dependent behaviors.

scholarly journals Evidence for a High Temperature Whisker Growth Mechanism Active in Tungsten during In Situ Nanopillar Compression

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2429
Author(s):  
Gowtham Jawaharram ◽  
Christopher Barr ◽  
Khalid Hattar ◽  
Shen Dillon
Keyword(s):  
Growth Mechanism ◽  
Laser Heating ◽  
Whisker Growth ◽  
Heating Surface ◽  
Surface Oxidation ◽  
Temperature Deformation ◽  
Compression Tests ◽  
Transmission Electron ◽  
Increasing Temperature

A series of nanopillar compression tests were performed on tungsten as a function of temperature using in situ transmission electron microscopy with localized laser heating. Surface oxidation was observed to form on the pillars and grow in thickness with increasing temperature. Deformation between 850 °C and 1120 °C is facilitated by long-range diffusional transport from the tungsten pillar onto adjacent regions of the Y2O3-stabilized ZrO2 indenter. The constraint imposed by the surface oxidation is hypothesized to underly this mechanism for localized plasticity, which is generally the so-called whisker growth mechanism. The results are discussed in context of the tungsten fuzz growth mechanism in He plasma-facing environments. The two processes exhibit similar morphological features and the conditions under which fuzz evolves appear to satisfy the conditions necessary to induce whisker growth.

Phase Formation, Stability and Superconducting Properties of Mechanically Alloyed Yttrium-Nickel-Borocarbides

1998 ◽  
Vol 547 ◽  
Author(s):  
L. Ledig ◽  
D. Hough ◽  
C.-G. Oertel ◽  
J. Eckert ◽  
W. Skrotzki
Keyword(s):  
Amorphous Phase ◽  
Amorphous State ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
X Ray ◽  
Milling Parameters ◽  
Transmission Electron ◽  
Nanocrystalline And Amorphous ◽  
Nickel Borocarbides

AbstractThe solid state reaction of YNi2B2C by mechanical alloying of elemental powders has been investigated by X-ray diffraction, transmission electron microscopy and susceptibility measurements. Depending on the ball milling parameters either nanocrystalline YNi2B2C or an amorphous phase can be produced. Crystallization of the amorphous phase by annealing at 893 K produces YNi2B2C as major and Ni2B as minor intermetallic compound. Superconductivity is only observed in the annealed state. However, the transition temperature is much lower than in arc-melted samples. This is discussed with respect to the nanocrystalline and amorphous state as well as deviations from stoichiometry produced by impurities introduced during milling.

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