Crystallization of Fe-Ni Based Amorphous Alloy

2007 ◽  
Vol 537-538 ◽  
pp. 185-190
Author(s):  
Dóra Janovszky ◽  
Jenő Sólyom ◽  
András Roósz ◽  
Zsolt Czigány
Keyword(s):  
Solid Solution ◽  
Amorphous Ribbon ◽  
Primary Crystallization ◽  
Nickel Silicide ◽  
Crystalline Solid ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Dsc Measurements ◽  
Different Temperatures

The devitrification of the Fe-Ni-B-Si amorphous ribbon was investigated by the differential scanning calorimetry (DSC) with scanning and isothermal methods. The devitrification of rapidly quenched ribbons is a multilevel process. On the basis of DSC investigations it was determined that crystallization occurs in three processes up to 700°C in the Fe40Ni40B16Si4 alloy. In the present work the first and second steps have been discussed. The first crystallization step involves the segregation of the Fe-Ni crystalline solid solution from the amorphous matrix. During the second crystallization phase, in addition to austenite, nickel silicide and two types of iron borides crystallize as well. The ribbons were relaxed at 380°C for 2 hours, following the pre-annealing at different temperatures. Pre-annealing was performed in the DSC within the temperature range elapsing from 395°C to 420°C. The preannealing at temperatures below the first exothermal DSC peak has an effect on the crystallization processes. After the pre-annealing the samples were investigated by DSC. The DSC peak of the first crystallization step shifts to higher temperatures and decrease its enthalpy. The scanning DSC measurements, applied after the isothermal pre-annealing, were performed in order to determine the fraction of the ribbon transformed in the primary crystallization step. The second DSC peak shifts to lower temperatures with a maximum of 4°C. The X-ray diffraction (XRD) analyses reveal that the lattice constant changes with the pre-annealing temperatures. Such observation was also supported by the circumstance that the composition of the Fe-Ni solid solution undergoes certain modifications.

Preparation and Property of Al87Ce3Ni8.5Mn1.5 Nanophase Amorphous Composites

2011 ◽  
Vol 412 ◽  
pp. 263-266
Author(s):  
Hong Wei Zhang ◽  
Li Li Zhang ◽  
Feng Rui Zhai ◽  
Jia Jin Tian ◽  
Can Bang Zhang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Phase ◽  
Volume Fraction ◽  
Material Structure ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Different Temperatures

The higher mechanical strength of Al87Ce3Ni8.5Mn1.5 nanophase amorphous composites has been obtained with two methods. The first nanophase amorphous composites are directly produced by the single roller spin quenching technology. The method taken for the second nanophase amorphous composites is at first to obtain amorphous single-phase alloy, followed by annealed at different temperatures .The formative condition, the microstructure, the particle size, the volume fraction of α-Al phase and microhardness of nanophase amorphous composites etc have been investigated and compared by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The microstructure of composites produced by the second method is higher than the former, the fabricated material structure of the system is more uniform and the process is easier to control.

scholarly journals Deformation induced martensite characterization in Fe-30%Ni-5%Cu alloy

2012 ◽  
Vol 48 (2) ◽  
pp. 259-264 ◽  
Author(s):  
E. Güler ◽  
M. Güler
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Dsc Measurements ◽  
Cu Alloy ◽  
The Face ◽  
Xrd Techniques ◽  
Scanning Electron

Deformation induced martensite properties were examined according to existing martensite morphology, crystallography and formation temperatures for different prior austenite homogenization conditions in Fe-30%Ni-5%Cu alloy. Scanning electron microscope (SEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques were employed to investigation. Scanning electron microscope observations showed elongated deformation induced martensite morphology in the austenite phase of alloy. As well, after deformation martensite start temperatures (Ms) were determined as -101?C and -105?C from DSC measurements for different homogenization conditions. In addition, X-ray diffraction analysis revealed the face centred cubic (fcc) of austenite phases and body centred cubic (bcc) deformation induced martensite phases for all studied samples.

Structure and properties of Al–Mg mechanical alloys

2003 ◽  
Vol 18 (8) ◽  
pp. 1827-1836 ◽  
Author(s):  
Mirko Schoenitz ◽  
Edward L. Dreizin
Keyword(s):  
Solid Solution ◽  
Energetic Materials ◽  
Amorphous Material ◽  
Bulk Composition ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Β Phase ◽  
Α Phase ◽  
Diffraction Microscopy

Mechanically alloys in the Al–Mg binary system in the range of 5–50 at.% Mg were produced for prospective use as metallic additives for propellants and explosives. Structure and composition of the alloys were characterized by x-ray diffraction microscopy (XRD) and scanning electron microscopy. The mechanical alloys consisted of a supersaturated solid solution of Mg in the α aluminum phase, γ phase (Al12Mg17), and additional amorphous material. The strongest supersaturation of Mg in the α phase (20.8%) was observed for bulk Mg concentrations up to 40%. At 30% Mg, the γ phase formed in quantities detectable by XRD; it became the dominating phase for higher Mg concentrations. No β phase (Al3Mg2) was detected in the mechanical alloys. The observed Al solid solution generally had a lower Mg concentration than the bulk composition. Thermal stability and structural transitions were investigated by differential scanning calorimetry. Several exothermic transitions, attributed to the crystallization of β and γ phases were observed. The present work provides the experimental basis for the development of detailed combustion and ignition models for these novel energetic materials.

Study on the Precipitation Sequence of Aged NCu30-4-2-1 Alloy by DSC

2014 ◽  
Vol 1061-1062 ◽  
pp. 35-38
Author(s):  
Yun Long Ai ◽  
Xiao Rui Shen ◽  
Wei Hua Chen ◽  
Yao Hui Xie
Keyword(s):  
Solid Solution ◽  
Differential Scanning Calorimetry ◽  
Supersaturated Solid Solution ◽  
Aging Treatment ◽  
Holding Time ◽  
Precipitation Sequence ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Different Temperatures ◽  
Block Distribution

NCu30-4-2-1 alloy was handled by solid solution at 950°Cfor 2h and then taking aging treatment at different temperatures and holding time. The microstructural evolution of NCu30-4-2-1 alloy in the process of aging treatment was investigated by metallographic microscope, X-ray diffractometer and differential scanning calorimetry. The results show that the phases of as-cast NCu30-4-2-1 alloy is composed by dendritic α-Ni-based solid solution and β-Ni3Si. After solid solution and aging treatment, the block distribution β-Ni3Si dissolves and many small granular dispersed distribution β'-Ni3Si precipitate out. With the increase of aging temperature and holding time, metastable β' tends to transform into stable β-Ni3Si. The precipitation sequence of aged NCu30-4-2-1alloy is supersaturated solid solution of α-Ni, GP zone, β'-Ni3Si and β-Ni3Si.

Nanocrystallization of gas atomized Cu47Ti33Zr11Ni8Si1 metallic glass

2006 ◽  
Vol 21 (3) ◽  
pp. 597-607 ◽  
Author(s):  
S. Venkataraman ◽  
S. Scudino ◽  
J. Eckert ◽  
T. Gemming ◽  
C. Mickel ◽  
...  
Keyword(s):  
Metallic Glass ◽  
Primary Crystallization ◽  
Nanocrystalline Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
High Resolution Tem ◽  
20 Nm ◽  
Annealing Experiments

Cu47Ti33Zr11Ni8Si1 metallic glass powder was prepared by gas atomization. Decomposition in the amorphous alloy and primary crystallization has been studied by differential scanning calorimetry (DSC), x-ray diffraction (XRD), and transmission electron microscopy (TEM). The glassy powder exhibits a broad DSC exotherm prior to bulk crystallization. Controlled annealing experiments reveal that this exotherm corresponds to a combination of structural relaxation and nanocrystallization. A uniform featureless amorphous contrast is observed in the TEM prior to the detection of nanocrystals of 4–6 nm in size. High-resolution TEM studies indicate that this nanocrystalline phase has a close crystallographic relationship with the γ–CuTi phase having a tetragonal structure. The product of the main crystallization event is also nanocrystalline, hexagonal Cu51Zr14, having dimensions of 20 nm. However, there is no evidence for possible amorphous phase separation prior to the nanocrystallization events.

Thermal and X-Ray Diffraction Studies of Doped and Undoped Single Crystal and Polycrystalline BaTiO3

1994 ◽  
Vol 360 ◽  
Author(s):  
L.G. Carreiro ◽  
J.V. Marzik ◽  
K.K Deb
Keyword(s):  
Solid Solution ◽  
Curie Temperature ◽  
Single Crystal ◽  
Dopant Concentration ◽  
Infrared Detection ◽  
Thermal Transition ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Mole Percent ◽  
X Ray

AbstractCalorimetric changes in a series of pure and doped single crystal and polycrystalline BaTiO3 were studied using differential scanning calorimetry over the temperature range of-110°C to 200°BC. The dopants, oxides of niobium and iron were varied from 0.5 to 8 mole percent, and strontium was varied from 5 to 35 mole percent. Endotherms were observed corresponding to three crystallographic transitions. The highest observed thermal transition corresponds to a tetragonal to cubic crystallographic transition and is also associated with the Curie temperature in these materals. Two additional endothermic transitions were also observed, an intermediatetemperature orthorhombic to tetragonal transition, and a low-temperature rhombohedral to orthorhombic transition. The three dopants decreased the crystallographic transition temperatures and Curie temperature as the dopant concentration was increased. X-ray diffraction was used to identify phases present and to determine the extent of solid solution. It is expected that these materials will display improved infrared detection as well as opto-electronic properties.

scholarly journals Effects of annealing parameters on phase, structure and thermochromic properties of VO2 (M) derived from nanostructured VO2(B)

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Hamdi Muhyuddin Barra ◽  
Soo Kien Chen ◽  
Nizam Tamchek ◽  
Zainal Abidin Talib ◽  
Oon Jew Lee ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Sem Images ◽  
X Ray ◽  
Thermogravimetric Analyzer ◽  
Different Temperatures ◽  
Thermochromic Properties ◽  
Scanning Electron

Abstract Synthesis of thermochromic VO2 (M) was successfully done by annealing hydrothermally-prepared VO2 (B) at different temperatures and times. Conversion of the metastable VO2 (B) to the thermochromic VO2 polymorph was studied using thermogravimetric analyzer (TGA) under N2 atmosphere. Moreover, the phase and morphology of the synthesized samples were studied using X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM), respectively. Accordingly, the XRD scans of all the annealed samples exhibited the presence of monoclinic VO2 (M), while the FE-SEM images of the samples showed the formation of nanorods and nanospheres, particularly those heated at high temperatures (650 °C and 700 °C). Meanwhile, differential scanning calorimetry (DSC) was used to measure the phase transition temperature (τc), hysteresis, and enthalpy of the prepared VO2. Based on these results, all samples displayed a τc of about 66 °C. However, the hysteresis was high for the samples annealed at lower temperatures (550 °C and 600 °C), while the enthalpy was very low for samples heated at lower annealing time (1.5 h and 1 h). These findings showed that crystallinity and nanostructure formation affected the thermochromic properties of the samples. In particular, the sample annealed at 650 °C showed better crystallinity and improved thermochromic behavior.

scholarly journals Estimating the Solubility, Solution Thermodynamics, and Molecular Interaction of Aliskiren Hemifumarate in Alkylimidazolium Based Ionic Liquids

Molecules ◽  
2019 ◽  
Vol 24 (15) ◽  
pp. 2807 ◽  
Author(s):  
Md. Khalid Anwer ◽  
Mohammad Muqtader ◽  
Muzaffar Iqbal ◽  
Raisuddin Ali ◽  
Bjad K. Almutairy ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Molecular Interaction ◽  
Solid Phase ◽  
Solution Thermodynamics ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Different Temperatures ◽  
Phase Evaluation ◽  
The Ideal

Estimating the solubility and solution thermodynamics parameters of aliskiren hemifumarate (AHF) in three different room temperature ionic liquids (RTILs), Transcutol-HP (THP) and water are interesting as there is no solubility data available in the literature. In the current study, the solubility and solution thermodynamics of AHF in three different RTILs, THP and water at the temperature range from 298.2 to 318.2 K under air pressure 0.1 MP were evaluated. The solid phase evaluation by Differential Scanning Calorimetry (DSC) and Powder X-ray Diffraction (PXRD) indicated no conversion of AHF into polymorph. The mole fraction solubility of AHF was found to be highest in 1-hexyl-3-methylimidazolium hexafluorophosphate (HMMHFP) ionic liquid (7.46 × 10−2) at 318.2 K. The obtained solubility values of AHF was regressed by the Apelblat and van’t Hoff models with overall root mean square deviations (RMSD) of 0.62% and 1.42%, respectively. The ideal solubility of AHF was higher compared to experimental solubility values at different temperatures. The lowest activity coefficient was found in HMMHFP, which confirmed highest molecular interaction between AHF–HMMHFP. The estimated thermodynamic parameters confirmed endothermic and entropy driven dissolution of AHF in different RTILs, THP, and water.

Study of Pseudoboehmite Synthesis by Sol-Gel Process

2006 ◽  
Vol 45 ◽  
pp. 260-265 ◽  
Author(s):  
Antônio Hortêncio Munhoz Jr. ◽  
Leila Figueiredo de Miranda ◽  
G.N. Uehara
Keyword(s):  
Sol Gel ◽  
Thermo Gravimetric Analysis ◽  
Ammonium Hydroxide ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Sol Gel Process ◽  
Different Temperatures ◽  
Sol Gel Synthesis

A pseudoboehmite was obtained by sol-gel synthesis using aluminum nitrate as precursor. It was used a 2n full factorial design for studying the effect of the temperature of synthesis, the concentration of ammonium hydroxide, and the radiation dose in the product of sol-gel synthesis. The product of the synthesis was analyzed by scanning electron microscopy, x-ray diffraction of the product (after firing the pseudoboehmite at different temperatures), and it was also analyzed the temperature of endothermic and exothermic transformations using the thermo gravimetric analysis (TG) and differential scanning calorimetry (DSC). The X-ray diffraction data show that α-alumina was obtained at 1100o C.

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