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BELL SYSTEM TECHNICAL JOURNAL 



are given the height vs. time curves for two different solders. It will 

 be seen that the curves cross each other, and that the consistency of 

 such samples would, if rated on such a basis, depend upon the time 

 selected for the comparison. In comparing two solders tested under 

 the same conditions, consideration must be given to both constants 

 of Equation 1 {k and b). For purposes of qualitative comparison an 

 equivalent procedure is to consider the sample heights at two different 

 times for each sample listed. 



J? 400 



Fig. 1 — Plot of a typical set of plasticity data. Solder No. 5 — 157° C. 



Comparison of Plasticity with Solid Liquid Ratio 



A summary of the results of the plasticity tests is given in Table II. 

 In this are included values of the percentage of liquid present in the 

 solder at the test temperature, calculated from the equilibrium 

 diagrams by the method advocated by Tammann.^ 



Sample heights after 30 minutes of compression are plotted in Fig. 4 

 against per cent liquid phase present under the conditions of test. 

 As one would expect, the points for any given solder can be placed on 

 a smooth curve, in which an increase in the proportion of liquid phase 



8 Gustav Tamniann, "A Textbook of Metallography." 



