What is a "divacancy" 1

[BobBartlett]

I recently came across an explanation that attributed a behavior (corrosion fatigue, if you must know) to the formation of "divacancies". Wiktionary defines a divacancy as:

A pair of vacancy defects in a crystal.

I am a member of ASM and a search through the journals available on their website (Like Met Trans A) did not reveal anything. I would not have expected it to.

Can someone please shed some insight on what a divacancy is?

Maybe a link to a website with an illustration, or a more intuitive explanation.

How is a divacancy different from a vacancy?

What is special about divacancies?

 

[metengr]

http://www.tf.uni-kiel.de/matwis/amat/def_en/kap_2/backbone/r2_1_1.html

 

[BobBartlett]

The link to the website with the mathematical derivation of the likelihood of existence of divalancies was certainly interesting.

May I supplement my posting to include a request for a short summary by a member, or an illustration of what a divalency "looks like" or why they are important to metallurgists?

 

[TVP]

Divacancies are discussed in terms of the anodic dissolution mechanism, which is used to explain stress corrosion cracking and corrosion fatigue. The following abstract is from a Met Trans article on the subject:

A unified mechanism of stress corrosion and corrosion fatigue cracking

http://www.springerlink.com/content/p122741634g44033/

Here is a Google Scholar link for keywords corrosion fatigue + divacancy:

http://scholar.google.com/scholar?hl=en&as_sdt=0,14&q="corrosion+fatigue"+divacancy

 

[BobBartlett]

Thank you for your reply TVP;

Funny that you would link me to that particular article. That is the very article that caused me to wonder what a divancancy is.

I understand what the article says about the action of divacancies, but what is a divacancy?

Is there any other mechanism that depends on divacancies?

What does one look like (obviously schematically)?

I guess I am a visual thinker.

 

[TVP]

There will be schematic representations in books devoted to crystallography, lattice defects, etc. Here are some examples:

Intrinsic Point Defects, Impurities, And Their Diffusion In Silicon

http://books.google.com.br/books?id...r_esc=y#v=onepage&q=divacancy lattice&f=false

A First-principles Methodology for Diffusion Coefficients in Metals and Dilute Alloys

http://books.google.com.br/books?id...vCA&redir_esc=y#v=onepage&q=divacancy&f=false

 

[BobBartlett]

TVP,

That was a terrific response. I wish I could give you more than one star. A link to a sketch, and another link to a concise description.

Exactly what I wanted.

Thanks again.

Bob

 

[TVP]

I aim to please.