no
as I understand grain size, NOT quenching is the key
let it cool as slowly as possible
you are after larger grain size
don't waste your time lapping it before annealing, it will 'move'

some info
http://www.key-to-metals.com/ViewArticle.asp?ID=25

http://innovations.copper.org/metall...etallurgy.html

http://www.completemetalworks.com/defs%5Cdefq.html (see second item - ??, not sure I agree)

http://www.asia.copper.org/acic/faqs_body.html
from above "What effect does heavy cold working have on the electrical conductivity of copper? It reduces by about 3%."

http://www.public.asu.edu/~jtsasu/ece350/Topic6.htm
"Excess vacancies may be introduced by quenching from high temperature, mechanical deformation, neutron irradiation."

a 3% change in conductivity is going to be a bit difficult to measure

Thank you for the links. I decided to look a little deeper into the role of quenching on defects, and found more supporting evidence:

http://www2.umist.ac.uk/material/res...u/al4cu01t.htm
"Rapid quenching also preserves the large number density of vacancies in the aluminium lattice from the high solution temperature." -edit: Not really relevant since the alloy is Al2Cu.

So it appears I will be lapping the block just enough to remove any impurities (oil, dirt), then annealing (is it correct to use the highest temp in the annealing range?), then fine lapping.

yea, go for the high temp
you g:oing to test before and after ?
(hopefully with enough mountings to understand the variance)

Sorry, my Digitec 5810 broke a few weeks ago, and I have yet to find an affordable replacement. So I have no means of accurate testing.

I annealed the copper for about 1hr at 1400F, and it came out red hot. Unfortunately, it quickly became covered in carbon as it cooled in the open air; the block was jet black (at least, I think the ambient air was the source of carbon, because the container was filled with argon during heating). And the base definitely deformed a bit: there are some tiny bumps where the copper seeped into the pores of the ceramic plate.

Should I measure electrical conductivity with an ohmmeter and identical strips of annealed and hard-drawn copper? Then I can simply use the Wiedemann-Franz Ratio to compute thermal conductivity.

Since87 probably is a better source than I
no problem re the conversion, the experimental part is tough
have you calculated how small the difference will be in ohms ?
-> you have an 8 1/2 digit ohmmeter ?

I suppose not, since I don't know of any that exist!

Well, then I truly have no way of measuring the annealing effect on conductance. What I am more interested in, though, is the effect on hardness. A reduction in Rockwell hardness from 54-62 to 47-57 seems worthwhile. Have any links relating material hardness to contact heat transfer?

OT: How do they measure resistance for conductors? Using very long, thin filaments?

The waterblock being covered with carbon seems odd to me. Atmospheric CO2 breaking down due to high temperatures but then the carbon doesn't burn off again as the piece cools? Perhaps the black material is some component of the copper alloy that oxidized? I'd be concerned that the mass of the material, or composition of the alloy might have changed enough to skew results. It would be better to allow the test piece to cool in the Argon to prevent this.

Also, heating the copper to the point that it flows could skew results due to changes in resistance resulting from thinning or thickening the copper in spots.

I could probably measure the resistance of a White Water baseplate to about 1% accuracy, but most waterblocks would be too thick for me to get a useful measurement.

It's much easier to measure the resistance of a reasonably thin, long wire, but it would be easy enough (for me) to measure the resistance of something like a 4" X 0.5" X 0.05" strip with 0.25" long slots cut into each end of the strip. (The slots in the ends are to provide 4 connection points. Two for connecting a current source and two for connecting a voltmeter.)

If you want to send me a strip like this, of the alloy you are using, I will measure the resistance of it, and send it back. You can anneal it and send it back to me, and I'll measure the resistance again.

Alternatively, I can send you a strip of copper and you can anneal it and send it back, but what I have available is some ultra pure oxygen free copper that won't necessarily reflect the behavior of your alloy. Also, the stuff I have is already annealed, so I will have to bend it, pound it with a hammer, whatever, to get it hardened. (I don't know exactly what the stuff I can get is. It was imported from Japan for some hare-brained scheme by a former coworker.)

The C102 alloy in my block is 99.95% pure copper (http://www.fiskalloy.com/w-alloys-pa...opc102110.html). I actually do not know the alloy of my cold plate, but it is probably high copper since it was a cutoff from an EDM electrode.

Since87, if your copper is already annealed, why not test it, then pound and bend it, and test it again? I wouldn't know how to make a strip that small, and I don't have any work-hardened C102 left.

Not carbon, theres too little in the air to have any impact. Its probably just copper oxide, a little thicker then usual due to temp.

The sheet copper is in the form of 0.5 m X 1 m sheets and I don't have a good way of cutting it off without at least somewhat work hardening it in the process.

I decided to test the easy way instead. I took about six foot of 22 gauge magnet wire, put an Amp through it with a current source, and measured the voltage across it. I then wrapped the wire around a pencil and unwrapped it about 5 times to work harden it, and measured the voltage drop again.

The resistance of the work hardened wire was 107.0% of the resistance of the unworked wire. Some of the increase of resistance may have been due to a bit of stretching of the wire as I wrapped it, but I'd guess that was under 1%. (Can't measure a change in length, since the worked wire is all kinked up.)

I think the most accurate and useful test would start by measuring the resistance of a hard piece and then annealing. This would minimize any mechanical changes to the piece. I do think the test I did, indicates that a gain of significantly more than 3% in conductivity may be attainable through annealing.

I can get you a piece of hard-drawn, work-hardened, oxygen-free, high-copper, but you would need to send it back quickly. Next Wed. is my last day at work, have to leave for uni. Two-day or overnight shipping shouldn't be too expensive for a small piece. Any size preference? Also, what do you think would be the best way to get maximum work hardening? I can use a mill, hydraulic press.... but since the piece is hard drawn, it should already be fairly hard. Or I could just smack it with a hammer a couple dozen times ;).