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Subject: Intermetallic Formation in Solder Joint

I am running a projects on metallurgical and microstructure analysis on
solder joint. A few doubts here.

1. What is the theory behind the intermetallic formation when soldered
  (62Sn/36Pb/2Ag paste) to Ni, Au, Cu and NiPd?

2. From the SEM/EDX, are we able to calculate the type of intermetallic
compound
   and how to do it?

3. Base on the calculation, can we relate the IMC formulation, eg Cu3Sn,to
the
   phase diagrame and how to explain it through the phase diagrame?

4. Why the bismuth in 48Sn/52Bi paste is brittle in nature? Can bismuth
blended
   into Sn or in the grain boundaries of CuSn IMC to embrittle the joint?

5. What will be the best available method to study the intermetallic
compound in
   detail and is there any books available on this subject?

6. Is the cooling rate important for the solder joint when reflowing through
the
   reflow profile and what will be the impact in term of microsturcture?

Regards,
YH Koh