Structural Characteristics of the Nanocrystalline Materials Synthesized by Completely Crystallizing Amorphous Alloys

1995 ◽  
pp. 349-361
Author(s):  
K. Lu
Keyword(s):  
Amorphous Alloys ◽  
Nanocrystalline Materials ◽  
Structural Characteristics

Crystallization of Ni-Cr-Si-B and Ni-Cr-Fe-Si-B Amorphous Alloys

2014 ◽  
Vol 216 ◽  
pp. 35-38 ◽  
Author(s):  
Cosmin Codrean ◽  
Dragoş Buzdugan ◽  
Ramona Lǎzar ◽  
Viorel Aurel Şerban ◽  
Ion Mitelea
Keyword(s):  
Thermal Stability ◽  
Chemical Composition ◽  
Rapid Solidification ◽  
Amorphous Alloys ◽  
Structural Characteristics ◽  
Glass Forming Ability ◽  
Glass Forming ◽  
Melting Temperatures ◽  
Dta Analysis ◽  
Thermal Stability Of

Ni based amorphous alloys with Si and B, which can also, contains Fe and Cr, prepared by rapid solidification, have low melting temperatures. This fact increases their susceptibility to be joined by welding and brazing. The glass forming ability (GFA) is conditioned also by the crystallization delay, due to certain chemical composition of the alloys. The thermal stability of these alloys was revealed by DTA analysis and structural characteristics were investigated by XRD. Applying an annealing at temperatures between 420°C and 540°C, with 30 minutes maintaining time, allowed the investigation of phase occurred during the crystallization and the estimation of the crystalline grains dimensions.

Application of Rietveld Method to the Structural Characteristics of some Bulk and Nanocrystalline Materials

2011 ◽  
Author(s):  
Sudhish Kumar ◽  
S. N. Dolia ◽  
R. K. Singhal ◽  
P. Predeep ◽  
Mrinal Thakur ◽  
...  
Keyword(s):  
Nanocrystalline Materials ◽  
Rietveld Method ◽  
Structural Characteristics

scholarly journals Synthesis, characterization and stability of amorphous alloys

2006 ◽  
Vol 38 (1) ◽  
pp. 83-92 ◽  
Author(s):  
Dragica Minic
Keyword(s):  
Electrochemical Synthesis ◽  
Amorphous Alloys ◽  
Structural Characteristics ◽  
Temperature Range ◽  
Amorphous Powders

In this paper the results of chemical and electrochemical synthesis of Fe-P, Fe-W and Fe-Ni amorphous powders, investigations of their structural characteristics, stability and processes of their relaxation and stabilization during heating in the temperature range of 20-1000oC are presented. .

The use of severe deformations for preparing bulk nanocrystalline materials from amorphous alloys

2004 ◽  
Vol 49 (9) ◽  
pp. 519-521 ◽  
Author(s):  
R. Z. Valiev ◽  
V. G. Pushin ◽  
D. V. Gunderov ◽  
A. G. Popov
Keyword(s):  
Amorphous Alloys ◽  
Nanocrystalline Materials ◽  
Bulk Nanocrystalline

AEM analysis of crystallization in Ti-based amorphous alloys

1983 ◽  
Vol 41 ◽  
pp. 270-271
Author(s):  
A.R. Pelton ◽  
A.F. Marshall ◽  
Y.S. Lee
Keyword(s):  
Magnetic Properties ◽  
Amorphous Alloys ◽  
Amorphous Materials ◽  
Isothermal Annealing ◽  
Amorphous Matrix ◽  
Nucleation And Growth ◽  
Current Interest ◽  
Amorphous Films ◽  
Electrical And Magnetic Properties

Amorphous materials are of current interest due to their desirable mechanical, electrical and magnetic properties. Furthermore, crystallizing amorphous alloys provides an avenue for discerning sequential and competitive phases thus allowing access to otherwise inaccessible crystalline structures. Previous studies have shown the benefits of using AEM to determine crystal structures and compositions of partially crystallized alloys. The present paper will discuss the AEM characterization of crystallized Cu-Ti and Ni-Ti amorphous films.Cu60Ti40: The amorphous alloy Cu60Ti40, when continuously heated, forms a simple intermediate, macrocrystalline phase which then transforms to the ordered, equilibrium Cu3Ti2 phase. However, contrary to what one would expect from kinetic considerations, isothermal annealing below the isochronal crystallization temperature results in direct nucleation and growth of Cu3Ti2 from the amorphous matrix.

A High Resolution Study of G.P. Zones in Aluminum - 4.2 at % Silver

1982 ◽  
Vol 40 ◽  
pp. 722-723 ◽  
Author(s):  
R. Gronsky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Computer Simulations ◽  
Structural Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Resolution Study

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.

SEM analysis of the change in the reaction rates with deposit structures in the copper-iron cementation system

1978 ◽  
Vol 36 (1) ◽  
pp. 456-457
Author(s):  
V. Annamalai ◽  
L.E. Murr
Keyword(s):  
Structural Characteristics ◽  
Secondary Electron Emission ◽  
Copper Deposit ◽  
Reaction Rates ◽  
Sem Analysis ◽  
Experimental Conditions ◽  
Major Drawback ◽  
Emission Mode ◽  
Scrap Iron ◽  
Image Position

Economical recovery of copper metal from leach liquors has been carried out by the simple process of cementing copper onto a suitable substrate metal, such as scrap-iron, since the 16th century. The process has, however, a major drawback of consuming more iron than stoichiometrically needed by the reaction.Therefore, many research groups started looking into the process more closely. Though it is accepted that the structural characteristics of the resultant copper deposit cause changes in reaction rates for various experimental conditions, not many systems have been systematically investigated. This paper examines the deposit structures and the kinetic data, and explains the correlations between them.A simple cementation cell along with rotating discs of pure iron (99.9%) were employed in this study to obtain the kinetic results The resultant copper deposits were studied in a Hitachi Perkin-Elmer HHS-2R scanning electron microscope operated at 25kV in the secondary electron emission mode.

Use of 2½ D imaging in analysis of NiTi martensite

1978 ◽  
Vol 36 (1) ◽  
pp. 610-611
Author(s):  
G. M. Michal
Keyword(s):  
Memory Effect ◽  
Monoclinic Phase ◽  
Reaction Path ◽  
Structural Characteristics ◽  
Salient Feature ◽  
Martensite Phase ◽  
Orientation Relationships ◽  
Low Symmetry ◽  
Hydride Phases ◽  
Unusual Shape

Several TEM investigations have attempted to correlate the structural characteristics to the unusual shape memory effect in NiTi, the consensus being the essence of the memory effect is ostensible manifest in the structure of NiTi transforming martensitic- ally from a B2 ordered lattice to a low temperature monoclinic phase. Commensurate with the low symmetry of the martensite phase, many variants may form from the B2 lattice explaining the very complex transformed microstructure. The microstructure may also be complicated by the enhanced formation of oxide or hydride phases and precipitation of intermetallic compounds by electron beam exposure. Variants are typically found in selfaccommodation groups with members of a group internally twinned and the twins themselves are often observed to be internally twinned. Often the most salient feature of a group of variants is their close clustering around a given orientation. Analysis of such orientation relationships may be a key to determining the nature of the reaction path that gives the transformation its apparently perfect reversibility.

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