Re: Hyperutectic Explained

From: Ohm347@aol.com
Date: Thu Feb 24 2000 - 22:55:06 EST


In a message dated 02/24/2000 6:10:02 PM Pacific Standard Time,
Jetmugg@aol.com writes:

four questions for you steve
1) what the hell do you do for a living?
2) what is a binary phase diagram?
3) at the eutectic temerature with the right eutectic composition are there
two different metals present?
4) why did most of that make sense?
derek

<< Okay - here's a quick lesson in metallurgy - a eutectic reaction is a
phase
 transformation whereby a liquid metal (single phase) cools though a certain
 temperature (the eutectic temperature), and transforms into two distinct
 solid phases. This reaction can be graphically expressed on a binary phase
 diagram. In the case of cast aluminum pistons, we would be talking about
the
 Aluminum-Silicon phase diagram. There is only one very specific composition
 at which the eutectic reaction occurs. Compositions which contain less
 Silicon and more Aluminum than this eutectic composition are said to be
 Hypoeutectic. Compositions which have a higher Silicon content, and
 correspondingly less Aluminum than the eutectic composition are said to be
 Hypereutectic.
 
 In the case of cast pistons, it just so happens that pistons cast from
 Hypereutectic compositions display mechanical and physical properties which
 make them more attractive for use as high-performance parts.
 
 SteveM. >>



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