Diffusion in Metallic Elements and Intermetallics

2009 ◽  
Vol 289-292 ◽  
pp. 15-38 ◽  
Author(s):  
Helmut Mehrer ◽  
Sergiy V. Divinski
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Ternary System ◽  
Functional Materials ◽  
Lattice Diffusion ◽  
Solid State Diffusion ◽  
Metallic Elements ◽  
Self Diffusion ◽  
Bcc Metals ◽  
State Diffusion

Starting from some fundamentals of solid-state diffusion, we remind the reader to the major techniques for lattice diffusion measurements. Self-diffusion is the most basic diffusion phenomenon in any solid. The paper covers main features of self-diffusion in pure fcc and bcc metals and some important facts about diffusion of substitutional solutes in metals. Binary intermetallics are compounds of two metals or of a metal and a semimetal. Their structures are different from those of the constituents. Some intermetallics are interesting functional materials others have attracted attention as high-temperature structural materials. The paper reviews some results mainly from our laboratory on diffusion in binary intermetallics from the systems Cu-Zn, Ni-Al, Fe-Al, Ni-Ge, Ni-Ga, Fe-Si, Ti-Al, Ni-Mn, Mo-Si and Co-Nb, which have been published in detail elsewhere. Some results for the ternary system Ni-Fe-Al are also mentioned.

Wagnerian Scaling Diffusion Kinetics

2008 ◽  
Vol 273-276 ◽  
pp. 594-601 ◽  
Author(s):  
César A.C. Sequeira
Keyword(s):  
Solid State ◽  
Point Defect ◽  
Parabolic Rate Constant ◽  
Scientific Basis ◽  
Lattice Diffusion ◽  
Solid State Diffusion ◽  
Protective Oxide ◽  
Oxidation Processes ◽  
Rate Limiting Step ◽  
State Diffusion

The reaction of a metal or alloy with an oxidising environment to form a scale often involves a diffusion process as the rate limiting step. The most protective oxide scales are slow growing, adherent to the substrate, and free of cracks or pores. The growth of these scales is typically by solid state diffusion of metal or oxygen ions that move via point defects in the oxide lattice. In 1933, C. Wagner established a scientific basis for oxidation processes controlled by solid state diffusion, with his celebrated derivation of the parabolic rate constant, which connects scaling rates, diffusion coefficients, point defect concentrations, point defect types, and effect of external parameters, e.g. pO2. These aspects are discussed in this paper. The importance of the Wagnerian theory is to provide a relatively simple model upon which more comprehensive models may be built. For many applications, the rate of degradation of the metal or alloy, owing to oxidation by lattice diffusion would be quite acceptable. Several examples of oxidation processes controlled by vacancy and/or interstitial diffusion will be discussed.

Joining of Ti3SiC2 with Ti–6Al–4V Alloy

2002 ◽  
Vol 17 (1) ◽  
pp. 52-59 ◽  
Author(s):  
N.F. Gao ◽  
Y. Miyamoto
Keyword(s):  
Solid State ◽  
Rate Constant ◽  
Liquid State ◽  
Parabolic Rate Constant ◽  
Diffusion Path ◽  
Solid State Diffusion ◽  
Diffusion Controlled ◽  
State Diffusion ◽  
Rate Controlled ◽  
Higher Temperature

The joining of a Ti3SiC2 ceramic with a Ti–6Al–4V alloy was carried out at the temperature range of 1200–1400 °C for 15 min to 4 h in a vacuum. The total diffusion path of joining was determined to be Ti3SiC2/Ti5Si3Cx/Ti5Si3Cx + TiCx/TiCx/Ti. The reaction was rate controlled by the solid-state diffusion below 1350 °C and turned to the liquid-state diffusion controlled with a dramatic increase of parabolic rate constant Kp when the temperature exceeded 1350 °C. The TiCx tended to grow at the boundarywith the Ti–6Al–4V alloy at a higher temperature and longer holding time. TheTi3SiC2/Ti–6Al–4V joint is expected to be applied to implant materials.

Investigation of the diffusion behavior in Sn-xAg-yCu/Cu solid state diffusion couples

2016 ◽  
Vol 686 ◽  
pp. 794-802 ◽  
Author(s):  
Yuan Yuan ◽  
Dajian Li ◽  
Yuanyuan Guan ◽  
Hans J. Seifert ◽  
Nele Moelans
Keyword(s):  
Solid State ◽  
Solid State Diffusion ◽  
Diffusion Couples ◽  
Diffusion Behavior ◽  
State Diffusion
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