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Re: [Phys-l] Help needed: Thermal conductivities of alloys?



My first inclination would be to try the simplest model where the k of
the alloy is the weighted sum of the ks of the ingredients with the
weights being the (fractional) percentages. For example if the alloy is
made up of metals A and B, you could try: k_alloy = p_A*k_A + p_B*k_B
where p_A and p_B are the fractional percentages (summing to unity) and
k_A and k_B are the individual thermal conductivities.

You could test how good this simple model is by finding the k of an
alloy which IS listed (with its constituent percentages and ks listed
also), construct the model for the tabulated case, and see how close you
come to the listed alloy value.

Don Polvani
Northrop Grumman Corp.
Annapolis, MD

-----Original Message-----
From: phys-l-bounces@carnot.physics.buffalo.edu
[mailto:phys-l-bounces@carnot.physics.buffalo.edu] On Behalf Of
Savinainen Antti
Sent: Tuesday, October 24, 2006 3:43 PM
To: phys-l@carnot.physics.buffalo.edu
Subject: [Phys-l] Help needed: Thermal conductivities of alloys?

Hi,

a student of mine has done interesting regerlation experiments with
different wires passing through a certain sized block of ice. The
diameter of the wires was the same as well as the temperature of the ice
block and the surroundings.

However, he has not been able to find thermal conductivities (k) for the
alloys he used. It is quite hard to analyse the results without the
values since he'd like to investigate the relation between the passing
time and k. So I'm resorting to your generous help: would anyone have a
data book reporting k's for the alloys mentioned below (alloys close to
the mentioned alloys would also be helpful since a complete match might
be a long shot). You might reply off-line (antti.savinainen(at)kuopio.fi
or antti.savinainen(at)luukku.com)

Alternatively, does someone know whow to calculate the k for an alloy if
the k's and percentages of metals forming the alloy are known?

Composition of Ag wire:

Cu 29.0 - 31.0 %
Ag 39.0 - 41.0 %
Zn 25.7 - 30.3 %
Sn 1.7 - 2.3 %


Composition of PCu wire
Cu 91.8 %
Ag 2.0 %
P 6.2 %

Composition of Al wire
Si 0.05 %
Mn 0.15 %
Al 94.65 %
Mg 5.0 %
Fe 0.15 %

Composition of the brass wire
Cu 60.20 %
Zn 38.28 %
Si 0.28 %
Sn 0.31 %
Mn 0.93 %

Composition of the
stainless steel wire
C 0.015
Si 0.85
Mn 1.75
Cr 18.5
Ni 12.0
Mo 2.7
Fe 64.2

Composition of the
steel wire
Fe 97.52
C 0.08
Si 0.90
Mn 1.50

Thanks in advance!

Antti

Antti Savinainen
Kuopio Lyseo High School
Finland
E-mail: <antti.savinainen@kuopio.fi>
Website: <http://kotisivu.mtv3.fi/physics/>


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