Effect of gas–solid interface on pore wall microstructure evolution during thermal melting of foamed ceramics

The liquid/solid composite technology has wide range of applications in the preparation of Fe-Al composite materials and structures. The diffusion-reaction zone (DRZ) formed in the liquid/solid interface has a great influence on their properties. The Al-Fe diffusion couple was prepared by using the insert technology and treated at 700°C-900°C. The microstructure evolution and growth mechanism of the DRZ in the Al/Fe liquid /solid interface were investigated. The result shows that the microstructure of Al/Fe liquid/solid diffusion couple after heat treatment (HT) is (Al+FeAl3)/FeAl3/Fe2Al5/Fe; Fe2Al5 is the only new phase during the heat preservation process, FeAl3 is formed by desolventizing during the cooling process. The growth of the Fe2Al5 is controlled by the chemical reaction of the Al atoms and Fe atoms before the Fe2Al5 continuous single-phase layer is formed; Once the continuous Fe2Al5 single-phase layer is formed, the growth of the Fe2Al5 mainly depends on the diffusion of Al atoms in the solid phase Fe2Al5 layer, and the reaction occurs in the solid/solid interface of the Fe2Al5 layer and iron. Precipitate is not found in the iron while the needlelike and strip FeAl3 precipitates appear in the aluminum; the density and size of the FeAl3 precipitates decrease gradually from the vicinity of interface to the distant.

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A Macro-Micro Model of Fusion Zone Microstructure Evolution in Mn-C Low-Alloy Steel Coupled With Thermal Stress Analysis

Volume 6B: Materials and Fabrication ◽

10.1115/pvp2015-45994 ◽

2015 ◽

Author(s):

Komeil Kazemi ◽

Andrei Artemev ◽

Jianguo Zhou ◽

John A. Goldak

Keyword(s):

Fusion Zone ◽

Alloy Steel ◽

Weld Pool ◽

Microstructure Evolution ◽

Room Temperature ◽

Stress And Strain ◽

Micro Model ◽

Low Alloy Steel ◽

Macro Model ◽

Solid Interface

A macro-micro-model for microstructure evolution in the fusion zone of a l.2 Mn and 0.11 C low-alloy steel is described. The macro-model is a 3D transient thermal analysis of a welded structure that resolves the weld pool with element size greater than 1 mm and time steps greater than 1 second. The micro-model has cell size of about 1 micron and time step size of about 10 micro-seconds with a grid of about 80×80×500 cells. The micro model is positioned on the liquid-solid interface of the weld pool in the macro-model. The boundary conditions for the micro-model are mapped from the macro-model. The micro-model solves the 3D transient solute diffusion equations for Mn and C. The micro-model computes the liquid-solid interface movement with local velocities determined by local temperature, compositions of solid and liquid phases and interface curvature to predict columnar or dendritic solidification structures. As the solid cools from the melting point to room temperature, the evolution of austenite, ferrite, pearlite, bainite and martensite phases are computed. The 3D transient stress due to temperature and phase changes is computed in the micro-model as it cools from the melting temperature to room temperature. At room temperature a micro-model tensile test is run to 4% strain. The macro-stress and strain is compared to the micro-stress and strain distributions. The model is intended to be used to initialize models of fracture, fatigue and creep in weld fusion zones.

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Atom-probe analysis of the solid-liquid interface

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100139755 ◽

1995 ◽

Vol 53 ◽

pp. 676-677

Author(s):

J.A. Panitz

Keyword(s):

Molecular Level ◽

Selective Adsorption ◽

Electronic Devices ◽

Atom Probe ◽

Chemical Agent ◽

Hostile Environment ◽

Solid Interface ◽

Solid Liquid Interface ◽

Solid Liquid ◽

Chemically Selective

The first few atomic layers of a solid can form a barrier between its interior and an often hostile environment. Although adsorption at the vacuum-solid interface has been studied in great detail, little is known about adsorption at the liquid-solid interface. Adsorption at a liquid-solid interface is of intrinsic interest, and is of technological importance because it provides a way to coat a surface with monolayer or multilayer structures. A pinhole free monolayer (with a reasonable dielectric constant) could lead to the development of nanoscale capacitors with unique characteristics and lithographic resists that surpass the resolution of their conventional counterparts. Chemically selective adsorption is of particular interest because it can be used to passivate a surface from external modification or change the wear and the lubrication properties of a surface to reflect new and useful properties. Immunochemical adsorption could be used to fabricate novel molecular electronic devices or to construct small, “smart”, unobtrusive sensors with the potential to detect a wide variety of preselected species at the molecular level. These might include a particular carcinogen in the environment, a specific type of explosive, a chemical agent, a virus, or even a tumor in the human body.

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