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FUSION AND SOLIDIFICATION 



8i 



of many investigators. It has already borne good 

 fruit, and is probably destined to bear still more 

 in time to come. Happily, Willard Gibbs lived 

 to see a general recognition of his genius, and 

 the reputations made of younger men who knew 

 how to extract and apply even single results 

 taken from the rich store hidden in his somewhat 

 abstruse pages. 



By the use of Gibbs' thermodynamic principles, 

 Roozeboom was able to trace the various possible 



ConcentraJiorv 



Fig. 9. 



forms which can be assumed by the two curves, 

 representing the compositions of the liquid and 

 solid phases in equilibrium with each other. The 

 simplest case indicated by the theory is shown in 

 Fig. 9. In regions above the higher curve, acb, 

 which is called the ''liquidus," all points represent 

 states completely liquid, while below the curve 

 adb, or *'solidus," the alloy is entirely solid. 

 Between these curves exist both liquid and solid 

 in various proportions. At a definite temperature, 



G 



