Impact of a Constant Magnetic Field on Decomposition of Cu-Be-Ni-Based Solid Solution

2018 ◽  
Vol 383 ◽  
pp. 173-179
Author(s):  
Regina Post ◽  
Julia V. Osinskaya ◽  
Sergiy V. Divinski ◽  
Alexander V. Pokoev ◽  
Gerhard Wilde
Keyword(s):  
Magnetic Field ◽  
Solid Solution ◽  
Grain Boundaries ◽  
Growth Rates ◽  
Constant Magnetic Field ◽  
Supersaturated Solid Solution ◽  
Discontinuous Precipitation ◽  
Magnetic Effect ◽  
Heat Treated ◽  
Precipitation Characteristics

Impact of a constant magnetic field on decomposition of supersaturated solid solution is investigated for the system Cu-Be-Ni. A technical bronze Cu-1.9Be-0.3Ni (in wt.%) was water-quenched after holding at 800°C (0.5 h) and subsequently heat treated at 325°C, 350°C and 400°C for 1 hour without and with application of a constant magnetic field of 0.7 T. The annealing in magnetic field is found to influence significantly the precipitation characteristics in diamagnetic Cu-based alloy, especially at 325°C. The nucleation barriers for discontinuous precipitation at grain boundaries are decreased, while the growth rates seem to be decreased, too, in magnetic field. A possible mechanism of the magnetic effect on discontinuous precipitation in the Cu-based is discussed.

scholarly journals Структура, диэлектрические и магнитодиэлектрические свойства керамики мультиферроика 0.5BiFeO-=SUB=-3-=/SUB=--0.5PbFe-=SUB=-0.5-=/SUB=-Nb-=SUB=-0.5-=/SUB=-O-=SUB=-3-=/SUB=-

2020 ◽  
Vol 62 (10) ◽  
pp. 1677
Author(s):  
А.В. Павленко ◽  
К.М. Жидель ◽  
Л.А. Шилкина
Keyword(s):  
Magnetic Field ◽  
Solid Solution ◽  
Dielectric Loss ◽  
Constant Magnetic Field ◽  
Room Temperature ◽  
Magnetoelectric Effect ◽  
Dielectric Characteristics ◽  
Temperature Range ◽  
Cubic Structure

The structure, dielectric characteristics, and magnetoelectric effect of multiferroic 0.5BiFeO3–0.5PbFe0.5Nb0.5O3 ceramics were studied. Ceramics are found to be pure. At room temperature, ceramics has a cubic structure close to а = 3.999(5) Å, which remains in the temperature range of 20–600 оС. It was shown that 0.5BiFeO3–0.5PbFe0.5Nb0.5O3 solid solution at Т < 200 оС combines both ferroelectric and antiferromagnetic properties. At room temperature in a constant magnetic field of 0.86 T, magnetodielectric coefficient and dielectric loss in the material are –0.4 % and –0.5 %, respectively.

Diffusion Along Migrating and Stationary Grain Boundaries: The Al-Zn System

1982 ◽  
Vol 21 ◽  
Author(s):  
W. Gust ◽  
M.B. Hintz ◽  
R. LuČić ◽  
B. PREDEL
Keyword(s):  
Solid Solution ◽  
Grain Boundaries ◽  
Discontinuous Precipitation ◽  
Eutectoid Reaction ◽  
Precipitation Reaction ◽  
Discontinuous Precipitation Reaction ◽  
Order Of Magnitude ◽  
Diffusion Rates ◽  
Discontinuous Coarsening ◽  
Zn Alloy

ABSTRACTThe discontinuous precipitation reaction has been studied in an Al-28a/o Zn solid solution. It appears that the diffusion rates determined by us for migrating grain boundaries are of the same order of magnitude as the values determined by Häβner (1974) for stationary grain boundaries. To the same statement have led results from the discontinuous coarsening reaction in an Al-29a/o Zn alloy (Fournelle et al., 1982) as well as from the eutectoid reaction in an Al-60a/o Zn alloy (Cheetham et al., 1971).

scholarly journals Precipitation Characteristics of the Metastable γ″ Phase in a Cu-Ni-Be Alloy

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1394 ◽  
Author(s):  
Zhiyuan Zhu ◽  
Yuanfei Cai ◽  
Kexing Song ◽  
Yanjun Zhou ◽  
Jiasheng Zou
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Transmission Electron Microscopy ◽  
Supersaturated Solid Solution ◽  
Reciprocal Lattice ◽  
Thermal Exposure ◽  
Face Centered Cubic ◽  
Transmission Electron ◽  
Precipitation Characteristics ◽  
Peak Aging

The precipitation sequence of a Cu-Ni-Be alloy is: α-Cu supersaturated solid solution → Guinier-Preston (G.P.) zones → metastable γ″ → γ′ → stable γ (NiBe) phase. The micro-hardness and electrical conductivity during the aging process were measured. The precipitation characteristics and the distribution of the γ″ phase, under peak aging conditions, were analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area diffraction pattern (SADP), and high-resolution transmission electron microscopy (HRTEM). The results show that the orientation relationship of the γ′′ phase/α-Cu matrix is: (001)p//(001)α; [100]p//[110]α (p: Precipitates, α: α-Cu supersaturated solid solution), which is in accordance with the Bain relationship in a FCC/BCC (face centered cubic/body centered cubic) structure, with the unique habit plane being {001}α. While the zone axis is parallel to [001]α, three forms of γ″ phases are distributed on the projection surface at the same time. The (001) reciprocal-lattice positions of γ′′ phase in SADP are diffusely scattered, which is consistent with the variation of the d(001) value of the γ′′ phase. The intra-range variation is related to the distortion of the (001) plane of the γ″ phase, due to interfacial dislocations and distortion strain fields. The lattice of the γ″ phase in the HRTEM images was measured as a = b = 0.259 ± 0.002 nm and c = 0.27–0.32 nm. With the increase of thermal exposure time, the stable γ phase has a NiBe phase structure (Standard Card Number: PDF#03-1098, a = b = c = 0.261 nm), and the long diffuse scattering spots will transform into single bright spots. The edge dislocation, generated by interfacial mismatch, promotes the formation of an optimal structure of the precipitated phase, which is the priority of growth in the direction of [110]p.

High-resolution EM study of submicrometer-grained Al-Mg solid solution alloys

1995 ◽  
Vol 53 ◽  
pp. 524-525
Author(s):  
Z. Horita ◽  
D. J. Smith ◽  
M. Furukawa ◽  
M. Nemoto ◽  
R. Z. Valiev ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
High Resolution ◽  
Grain Boundaries ◽  
Energy State ◽  
High Energy ◽  
Grain Structure ◽  
Boundary Structure ◽  
Solid Solution Alloy ◽  
Average Grain Size

It is possible to produce metallic materials with submicrometer-grained (SMG) structures by imposing an intense plastic strain under quasi-hydrostatic pressure. Studies using conventional transmission electron microscopy (CTEM) showed that many grain boundaries in the SMG structures appeared diffuse in nature with poorly defined transition zones between individual grains. The implication of the CTEM observations is that the grain boundaries of the SMG structures are in a high energy state, having non-equilibrium character. It is anticipated that high-resolution electron microscopy (HREM) will serve to reveal a precise nature of the grain boundary structure in SMG materials. A recent study on nanocrystalline Ni and Ni3Al showed lattice distortion and dilatations in the vicinity of the grain boundaries. In this study, HREM observations are undertaken to examine the atomic structure of grain boundaries in an SMG Al-based Al-Mg alloy.An Al-3%Mg solid solution alloy was subjected to torsion straining to produce an equiaxed grain structure with an average grain size of ~0.09 μm.

Carbide precipitation and chromium depletion on coherent twin boundaries in deformed 304 stainless steels

1992 ◽  
Vol 50 (2) ◽  
pp. 1216-1217
Author(s):  
A.H. Advani ◽  
L.E. Murr ◽  
D.J. Matlock ◽  
W.W. Fisher ◽  
P.M. Tarin ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Stainless Steels ◽  
Interfacial Free Energy ◽  
Carbide Precipitation ◽  
Twin Boundaries ◽  
Invariant Structure ◽  
Heat Treated ◽  
Constant Structure ◽  
Cr Depletion

Coherent annealing-twin boundaries are constant structure and energy interfaces with an average interfacial free energy of ∼19mJ/m2 versus ∼210 and ∼835mJ/m2 for incoherent twins and “regular” grain boundaries respectively in 304 stainless steels (SS). Due to their low energy, coherent twins form carbides about a factor of 100 slower than grain boundaries, and limited work has also shown differences in Cr-depletion (sensitization) between twin versus grain boundaries. Plastic deformation, may, however, alter the kinetics and thermodynamics of twin-sensitization which is not well understood. The objective of this work was to understand the mechanisms of carbide precipitation and Cr-depletion on coherent twin boundaries in deformed SS. The research is directed toward using this invariant structure and energy interface to understand and model the role of interfacial characteristics on deformation-induced sensitization in SS. Carbides and Cr-depletion were examined on a 20%-strain, 0.051%C-304SS, heat treated to 625°C-4.5h, as described elsewhere.

EELS Measurement of the Local Electronic Structure of Copper Atoms Segregated to Aluminum Grain Boundaries

1996 ◽  
Vol 54 ◽  
pp. 342-343
Author(s):  
S.J. Splinter ◽  
J. Bruley ◽  
P.E. Batson ◽  
D.A. Smith ◽  
R. Rosenberg
Keyword(s):  
Electronic Structure ◽  
Grain Boundaries ◽  
Boundary Segregation ◽  
Thin Layers ◽  
Nominal Composition ◽  
Spatially Resolved ◽  
Service Lifetime ◽  
Heat Treated ◽  
Probe Size ◽  
Local Electronic Structure

It has long been known that the addition of Cu to Al interconnects improves the resistance to electromigration failure. It is generally accepted that this improvement is the result of Cu segregation to Al grain boundaries. The exact mechanism by which segregated Cu increases service lifetime is not understood, although it has been suggested that the formation of thin layers of θ-CuA12 (or some metastable substoichiometric precursor, θ’ or θ”) at the boundaries may be necessary. This paper reports measurements of the local electronic structure of Cu atoms segregated to Al grain boundaries using spatially resolved EELS in a UHV STEM. It is shown that segregated Cu exists in a chemical environment similar to that of Cu atoms in bulk θ-phase precipitates.Films of 100 nm thickness and nominal composition Al-2.5wt%Cu were deposited by sputtering from alloy targets onto NaCl substrates. The samples were solution heat treated at 748K for 30 min and aged at 523K for 4 h to promote equilibrium grain boundary segregation. EELS measurements were made using a Gatan 666 PEELS spectrometer interfaced to a VG HB501 STEM operating at 100 keV. The probe size was estimated to be 1 nm FWHM. Grain boundaries with the narrowest projected width were chosen for analysis. EDX measurements of Cu segregation were made using a VG HB603 STEM.

Direct Observation of Monolayer Zones in Al-wt 4% Cu

1990 ◽  
Vol 48 (1) ◽  
pp. 14-15
Author(s):  
B. Jouffrey ◽  
D. Dorignac ◽  
A. Bourret
Keyword(s):  
Solid Solution ◽  
Synchrotron Radiation ◽  
Direct Observation ◽  
Supersaturated Solid Solution ◽  
Original Model ◽  
X Ray ◽  
Image Position

Since the early works on GP zones and the model independently proposed by Preston and Guinier on the first steps of precipitation in supersaturated solid solution of aluminium containing a few percent of copper, many works have been performed to understand the structure of different stages in the sequence of precipitation.The scheme which is generally admitted can be drawn from a work by Phillips.In their original model Guinier and Preston analysed a GP zone as composed of a single (100) copperrich plane surrounded by aluminum atomic planes with a slightly shorter distance from the original plane than in the solid solution.From X-ray measurements it has also been shown that GP1 zones were not only copper monolayer zones. They could be up to a few atomic planes thick. Different models were proposed by Guinier, Gerold, Toman. Using synchrotron radiation, proposals have been recently made.

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