

V. Eutectic Research. No- 1. The Alloys of Lead and Tin. 



Bij WALTER ROSENHAIN, B.A., B.C.E., with P. A. TUCKEK. 



(From the National Physical Laboratory.) 



Communicated by R. T. GLAZEBROOK, M.A., F.R.S. 



Received June 17, Read June 25, 1908. 



[PLATES 5-9.] 



THE investigations described in the present paper were begun in pursuance of a 

 scheme for the systematic investigation of the constitution and properties of eutectic 

 alloys. The first steps in such an investigation naturally consist in the preparation of 

 some samples of typical eutectic bodies in a state approaching purity, followed by the 

 determination of their chemical composition and constitution. Since a large number 

 of systems of binary alloys have been closely studied and diagrams claiming to set 

 forth their equilibrium conditions have been published, it was thought at the outset 

 that there would be no difficulty in finding a number of typical eutectic alloys whose 

 chemical composition was accurately known and whose constitution could be deduced 

 from the corresponding equilibrium diagrams. The eutectic of the lead-tin series was 

 chosen as a suitable example for early study partly because the alloys of this series 

 are very easily prepared and manipulated, but principally because this series has 

 hitherto been regarded as the typical example of the simplest class of binary alloys, 

 viz., those in which the two metals are mutually insoluble in the solid state. 



In the preparation of the eutectic alloy of lead and tin on the basis of the data 

 given by ROBERTS- AUSTEN* it was found that the results of the present experiments 

 did not agree well with the data given by that author. Thus, while ROBERTS- AUSTEN 

 gives the composition of the eutectic alloy as approximately 31 per cent, of lead and 

 69 per cent, of tin, the present investigation shows the composition of this alloy to be 

 very nearly 37 per cent, of lead and 63 per cent, of tin. Further, the diagram given 

 by ROBERTS- AUSTEN indicates that solid lead and tin are nearly mutually insoluble in 

 the solid state, or, in other words, that the eutectic alloy is present in alloys quite 

 near the two ends of the series. As regards the lead end of the series, such serious 



* ROBERTS- AUSTEN, ' Fourth Report to the Alloys Research Committee, Inst. Mech. Eng., 1897.' 

 VOL. CCIX A 445, N 17.11.0 



