Inge,
There are no short answers to your questions, with the exception "it depends". Intermetallics (particularly finely dispersed) can increase UTS of solder.
With large platelets, one should consider the role of sliding at the solder/platelets interface (with creation of stress concentration), as well as their "strength"/brittleness.
The cooling rate will play a significant role in the shape.
The major driving force is thermodynamics.
Vladimir
SENTEC Testing Laboratory Inc.
11 Canadian Road, Unit 7.
Scarborough, ON M1R 5G1
Tel: (416) 899-1882
Fax: (905) 882-8812
www.sentec.ca
-----Original Message-----
From: Inge <[log in to unmask]>
Sender: TechNet <[log in to unmask]>
Date: Tue, 23 Nov 2010 22:28:21
To: <[log in to unmask]>
Reply-To: TechNet E-Mail Forum <[log in to unmask]>,
Inge <[log in to unmask]>
Subject: [TN] Ductile to Brittle transition
Hi,
have a few questions on Konstantina's and your report.
1. If you place steel bars or steel nets in the concrete, the strength will
increase significantly, but the IMC plates and needles in the sollder joint
do the opposite. How com?
2. Why are so many geometries created? Large plates, small plates, needles,
bars, all in a chaotic oder.
3. What causes the predominant brittleness, size of IMCs or geometric form
or anything else?
4. What is the major driving force to build up the IMC structure,
percentage of xx in the solder, or solidification speed or what?
Inge
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