Estimating The Elastic Properties Of An Alloy 4

[edwync]

I am trying to estimate the elastic properties of several alloys as accurately but simply as possible. I am a computer engineer not a materials engineer, so I am struggling here!

I have heard that the youngs modulus of an alloy may not differ greatly from those of its elements.

Does this mean that I can calculate the youngs modulus proportionately based on the quantities of each element in a given alloy?

eg:
bronze composed from
88% copper, 12% tin
128 GPa copper, 50 GPa tin
=(0.88*128)+(0.12*50)
=112,64+6
=118.64 GPa bronze young's modulus

If so, would I also be able to calculate the Poisson Ratio in the same way, or is this harder because of the way the different elements bond in the alloy at the molecular level.

If this is too simple, then what are the best methods of estimating youngs modulus and poisson ratio of an alloy based on its composite elements, or is this not possible with any degree of accuracy?

Thanks for reading!

 

[cloa]

That's a reasonable approach but better to use

http://www.Matweb.com

to find your material or something close. The inaccuracies come out with different crystallographic structures- if two metals have the same arrangement of atoms then a mixture of the atoms with the same arrangement is the same as a proportion of atoms in the alloy (just as you calculated).

 

[edwync]

Thanks for the response, Cloa.

So does that mean that an alloy of copper (face-centered cubic structure - FCC) and silver (also FCC) can be calculated simply as above, but that tungsten (body-centered cubic - BCC) and silver (FCC) cannot be? Or is that too much of a simplification?

 

[EdStainless]

You have the correct idea. Different structures have different deformation and slip characteristics.
Just look up the specific alloys that you are interested in. manufacturers data sheets will have modulus and other physical property data.

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[blacksmith37]

The one outlier that I know of is cast iron; the modulus depends on the amount and type of graphite.

 

[edwync]

Thanks for the replies. I can't find elasticity details for most of the alloys I am interested in on Matweb unfortunately.

They are materials used in the jewelry trade such as gold alloys (gold alloyed with copper/silver). Perhaps Matweb is biased towards industrial/research materials.

I can find the alloys in Matweb, but the poisson ratio and youngs modulus isn't included for any of them.

Gold, Au; 18K, Yellow (UNS P00255)
Gold, Au; 14K, Yellow (UNS P00180)
Gold, Au; 10K, Yellow (UNS P00115)
Gold, Au; 18K, Green (UNS P00280)
Gold, Au; 14K, Green (UNS P00180)
Gold, Au; 10K, Green (UNS P00140)
Gold, Au; 18K, Red (UNS P00285)
Gold, Au; 14K, Red (UNS P00170)
Gold, Au; 10K, Red (UNS P00145)

Are there any other materials references you can think of that might have the elastic properties for these alloys?

 

[Maui]

Edwync, you should read the following FAQ to understand how the value of the elastic modulus can be calculated based upon the microstructure and the type of bonding:

faq330-1441

Maui

http://www.EngineeringMetallurgy.com

 

[EdStainless]

They are listed in the ASM handbooks, and actually there is not that much variation in them.
I would look them up for you but I am on the road.


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