On Tue, 06 Jul 2004 01:21:22 GMT, Seppo Renfors
wrote:



Eric Stevens wrote:

On Mon, 05 Jul 2004 01:49:44 GMT, Seppo Renfors
wrote:

They are a result of the small air bubbles trapped throughout the metal
caused by melting it in less than controlled conditions.

I can understand that during a melting process where molecules are at
their most active, some reaction to air and a certain amount of mixing
can occur. What I find difficult is that an annealing process causes
bubbles -UNLESS it is overheated to a melting point locally. How else
does something get INTO the metal to cause bubbles when it is pure to
begin with?

At high temperatures oxygen is soluble in copper.

So you say the copper has to be melted at that point, as you claim
"soluble" - in a SOLUTION! As I thought...

Oxygen is soluble in copper at temperatures below its melting point.
In much the same way hydrogen is soluble in iron at ambient
temperatures. Look up 'hydrogen embrittlement' if you don't believe
me.




Eric Stevens