Pure Copper?
 

I picked up a piece of copper from the local scrap metal place. Is there anyway I can tell if it's a copper/zinc, copper/ tin, or pure coppy alloy?

W/ pure copper how easy is it to cut w/ a regular pocket knife?

-Cheese Eater, and Beaver Beater

Re: Pure Copper?
 

Pure copper alloy??? :D

Copper is not an alloy, it is very soft, but any of the "alloy" (copper mixed with other metals) versions will be soft to. Pretty good chance it is just C110 copper, not alloy. Wouldn't say it is "easy" to cut with a knife, but you should be able to get a shaving off a corner maybe. If it looks like copper and not brass it should be fine. Copper and zinc (maybe others) = Brass. Much more yellow color instead of copper color.

confirmed,

if u can get us a pic, that would help,

this one has one WB half in brass and one half in copper

the red part is copper, the yellow part is brass
http://users.skynet.be/donsole/wb1010.jpg

the next pic is all brass to show ya
http://users.skynet.be/donsole/wb1005.jpg

LOL, an "alloy" by definition is a composition of mixed materials. Whether a pure material or an alloy, things like hardness are insufficient to identify materials. This is because the hardness, yield strength, and many other properties are a function of more than composition. Cold working, annealing, heat treating, etc., all affect properties like hardness.

I don't have a sure fire method for identifying your material, but can guarantee that there are many ways that don't work.

if you can cut it with a knife and its not very thin, its got lead or gold in it...

You might be able to make an educated guess at the material type if you worked with the material (i.e. worked with the material in a milling machine). But, that's all it would be: a guess. Your only way to tell for sure is to do analysis to determine the proportion of elements in the sample. Spectroscopy would work. myv65 really hit this one on the head.

I realized after reading it pure alloy was an oxymoron. But didn't care, I meant copper/zinc alloy, copper/ tin alloy, or pure coppy?

But didn't feel like typing alloy twice :p

I know it is definately not brass. But wasn't sure how common copper mixed w/ something else is. (EXCLUDING BRASS :p, if I must be totally specific.)

if it seems to like it isnt nearly pure copper, its most likely thats its a piece of copper which has a high amount of impurities in it I would think

Define pure.

Without being anal, you don't really get pure materials, as Hydrogen18 rightly stated.

The problem with copper is that small additions of just about anything wreck it's thermal characteristics. However, working in our favour is the fact that copper is rarely used for anything other than electrical or thermal applications, so most copper available is as pure as is commercially viable.

8-ball

One of the best ways to determine what a material is is to look at it under a high powered microscope. Different impurities and alloying additions often have a large effect on the microstructure, and combined with a hardness test, you can usually get pretty conclusive results.

Alternatively you could run EDX analysis in an electron microscope (SEM or TEM), though this would only tell you if it were "roughly" pure due to the low mass sensitivity of this technique.

SIMS analysis has the highest mass sensitivity, though you need to know what you're looking for to be able to calibrate the machine.

Finally, for complete overkill, you could run it through the 3D position sensitive time of flight atom probe. This will give you the location and type of each atom within a small sample.

However, I fear most of these techniques would be taking it a little over the top.

8-ball

Pure copper is hard if not impossible to come by but copper tends to be reddish or pinkish in color. Annealing tends to change this color a bit too. Copper mixed with tin, silver, lead, zinc(the popular copper alloys) added it tends to look more of the color brass with bronze a bit darker. There is one copper alloy that tends to look almost purple in color.

Here's a link that might help out. With so many alloys, it's hard to tell exactly by look without getting scientific.