Microstructural changes of nanocrystalline nickel during cold rolling

The use of an acoustic nonlinear response has been accepted as a promising alternative for the assessment of micro-structural damage in metallic solids. However, the full mechanism of the acoustic nonlinear response caused by the material micro-damages is quite complex and not yet well understood. In this paper, the effect of material microstructural evolution on acoustic nonlinear response of ultrasonic waves is investigated in rolled copper and brass. Microstructural evolution in the specimens is artificially controlled by cold rolling and annealing treatments. The correlations of acoustic nonlinear responses of ultrasonic waves in the specimens corresponding to the microstructural changes are obtained experimentally. To eliminate the influence of attenuation, which was induced by microstructural changes in specimens, experimentally-measured nonlinear parameters are corrected by an attenuation correction term. An obvious decrease of nonlinearity with the increase of grain size is found in the study. In addition, the influences of material micro-damages introduced by cold rolling on the acoustic nonlinear response in specimens are compared with the ones of grain boundaries controlled by heat treatment in specimens. The experimental results show that the degradation of material mechanical properties is not always accompanied by the increase of acoustic nonlinearity generated. It suggested that the nonlinear ultrasonic technique can be used to effectively characterize the material degradations, under the condition that the variations of grain sizes in the specimens under different damage states are negligible.

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Quantitative defect evolution of nanocrystalline nickel during cold rolling

Philosophical Magazine Letters ◽

10.1080/09500839.2011.652686 ◽

2012 ◽

Vol 92 (4) ◽

pp. 202-210 ◽

Cited By ~ 4

Author(s):

H.T. Ni ◽

X.Y. Zhang

Keyword(s):

Cold Rolling ◽

Nanocrystalline Nickel ◽

Defect Evolution

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Microstructural Changes of Cementite in Pearlite Steel by Cold Rolling

Materia Japan ◽

10.2320/materia.43.1022 ◽

2004 ◽

Vol 43 (12) ◽

pp. 1022-1022

Author(s):

Yoshikazu Todaka ◽

Minoru Umemoto ◽

Koichi Tsuchiya ◽

Akifumi Ohno ◽

Mayumi Suzuki

Keyword(s):

Cold Rolling ◽

Microstructural Changes

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Phenomena Associated with Oxygen in Titanium

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100061562 ◽

1967 ◽

Vol 25 ◽

pp. 310-311

Author(s):

E. U. Lee ◽

P. A. Garner ◽

J. S. Owens

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Electron Microscope ◽

Microstructural Changes ◽

Electrolytic Polishing ◽

Interstitial Impurities ◽

Thin Foils ◽

Transmission Electron ◽

Iodide Titanium ◽

Alpha Titanium

Evidence for ordering (1-6) of interstitial impurities (O and C) has been obtained in b.c.c. metals, such as niobium and tantalum. In this paper we report the atomic and microstructural changes in an oxygenated c.p.h. metal (alpha titanium) as observed by transmission electron microscopy and diffraction.Oxygen was introduced into zone-refined iodide titanium sheets of 0.005 in. thickness in an atmosphere of oxygen and argon at 650°C, homogenized at 800°C and furnace-cooled in argon. Subsequently, thin foils were prepared by electrolytic polishing and examined in a JEM-7 electron microscope, operated at 100 KV.

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Tensile Creep of Y-Si3N4: II. Cavitation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100089172 ◽

1991 ◽

Vol 49 ◽

pp. 972-973 ◽

Cited By ~ 1

Author(s):

B. J. Hockey ◽

S. M. Wiederhorn

Keyword(s):

Silicon Nitride ◽

Creep Rupture ◽

Tensile Creep ◽

Sintering Aids ◽

Microstructural Changes

ATEM has been used to characterize three different silicon nitride materials after tensile creep in air at 1200 to 1400° C. In Part I, the microstructures and microstructural changes that occur during testing were described, and consistent with that description the designations and sintering aids for these materials were: W/YAS, a SiC whisker reinforced Si3N4 processed with yttria (6w/o) and alumina (1.5w/o); YAS, Si3N4 processed with yttria (6 w/o) and alumina (1.5w/o); and YS, Si3N4 processed with yttria (4.0 w/o). This paper, Part II, addresses the interfacial cavitation processes that occur in these materials and which are ultimately responsible for creep rupture.

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Microanalytical Identification of a New Zr-Nb-Fe Phase

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100134259 ◽

1990 ◽

Vol 48 (2) ◽

pp. 132-133

Author(s):

O.T. Woo ◽

G.J.C. Carpenter

Keyword(s):

Trace Elements ◽

Cold Rolling ◽

Proportionality Factor ◽

Tube Material ◽

X Ray ◽

Metal Foils ◽

Arc Melting ◽

Intermetallic Particles ◽

Intermetallic Precipitates ◽

Cold Worked

To study the influence of trace elements on the corrosion and hydrogen ingress in Zr-2.5 Nb pressure tube material, buttons of this alloy containing up to 0.83 at% Fe were made by arc-melting. The buttons were then annealed at 973 K for three days, furnace cooled, followed by ≈80% cold-rolling. The microstructure of cold-worked Zr-2.5 at% Nb-0.83 at% Fe (Fig. 1) contained both β-Zr and intermetallic precipitates in the α-Zr grains. The particles were 0.1 to 0.7 μm in size, with shapes ranging from spherical to ellipsoidal and often contained faults. β-Zr appeared either roughly spherical or as irregular elongated patches, often extending to several micrometres.The composition of the intermetallic particles seen in Fig. 1 was determined using Van Cappellen’s extrapolation technique for energy dispersive X-ray analysis of thin metal foils. The method was employed to avoid corrections for absorption and fluorescence via the Cliff-Lorimer equation: CA/CB = kAB · IA/IB, where CA and CB are the concentrations by weight of the elements A and B, and IA and IB are the X-ray intensities; kAB is a proportionality factor.

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TEM study of amorphization of Cu and Ti foils by cold-rolling

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100173868 ◽

1990 ◽

Vol 48 (4) ◽

pp. 146-147

Author(s):

W. A. Chiou ◽

N. L. Jeon ◽

Genbao Xu ◽

M. Meshii

Keyword(s):

Solid State ◽

Cold Rolling ◽

High Energy ◽

Rapid Quenching ◽

Vapor Condensation ◽

Metallic Alloys ◽

Solid State Reactions ◽

High Energy Particle ◽

Amorphous Metallic Alloys ◽

Thin Foils

For many years amorphous metallic alloys have been prepared by rapid quenching techniques such as vapor condensation or melt quenching. Recently, solid-state reactions have shown to be an alternative for synthesizing amorphous metallic alloys. While solid-state amorphization by ball milling and high energy particle irradiation have been investigated extensively, the growth of amorphous phase by cold-rolling has been limited. This paper presents a morphological and structural study of amorphization of Cu and Ti foils by rolling.Samples of high purity Cu (99.999%) and Ti (99.99%) foils with a thickness of 0.025 mm were used as starting materials. These thin foils were cut to 5 cm (w) × 10 cm (1), and the surface was cleaned with acetone. A total of twenty alternatively stacked Cu and Ti foils were then rolled. Composite layers following each rolling pass were cleaned with acetone, cut into half and stacked together, and then rolled again.

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A TEM microscopical investigation of the magnetic domain structure of a metastable austenitic stainless steel

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100171213 ◽

1994 ◽

Vol 52 ◽

pp. 696-697

Author(s):

G. Fourlaris ◽

T. Gladman

Keyword(s):

Tensile Strength ◽

Stainless Steel ◽

Austenitic Stainless Steel ◽

Cold Rolling ◽

Solution Treatment ◽

Magnetic Domain ◽

High Strength ◽

Medium Carbon Steel ◽

Magnetic Characteristics ◽

Metastable Austenitic Stainless Steel

Stainless steels have widespread applications due to their good corrosion resistance, but for certain types of large naval constructions, other requirements are imposed such as high strength and toughness , and modified magnetic characteristics.The magnetic characteristics of a 302 type metastable austenitic stainless steel has been assessed after various cold rolling treatments designed to increase strength by strain inducement of martensite. A grade 817M40 low alloy medium carbon steel was used as a reference material.The metastable austenitic stainless steel after solution treatment possesses a fully austenitic microstructure. However its tensile strength , in the solution treated condition , is low.Cold rolling results in the strain induced transformation to α’- martensite in austenitic matrix and enhances the tensile strength. However , α’-martensite is ferromagnetic , and its introduction to an otherwise fully paramagnetic matrix alters the magnetic response of the material. An example of the mixed martensitic-retained austenitic microstructure obtained after the cold rolling experiment is provided in the SEM micrograph of Figure 1.

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