434 SUMMARY OF CURRENT RESKARCHES. 



Metallography, etc. 



Reciprocal Solubility of Copper and Lead.* — By chemical and 

 microscopical methods B. Bogitch has shown that a molten alloy of 

 copper and lead separates into two layers when the copper content is 

 between 34* 5 and 87 p. c. and the temperature is between 940° and 

 975° C. 



Gold-cadmium Alloys. f — P. Saldau includes a detailed description 

 of the microstructure of numerous gold-cadmium alloys in an account 

 of his investigation of this binary system. The alloys were examined 

 as cast and also after annealing at 250° or 350° C. for ten days. Two 

 compounds occur, AuCd and AuCdg, which enter into solid solution 

 with their components through a limited range. 



Persistent Brittleness in Steel. | — V. Bernard and A. Portevin 

 have examined a piece of medium-carbon steel which had broken in 

 use. Its brittleness was thought to be due to the overheating which 

 was indicated by the coarse structure. Quenching from S50 C. followed 

 by reheating to 700° C. replaced the coarse structure by a fine one, but 

 impact tests showed that the brittleness had not been removed. A more 

 careful microscopic examination then revealed the presence of indistinct 

 narrow bands of ferrite forming a very coarse network. Lines of 

 minute holes and inclusious in the middle of these ferrite bands formed 

 surfaces of weakness, resulting in brittleness which could not be removed 

 by any form of heat-treatment. The network of small holes and 

 inclusions is regarded as the remains of an early and extremely coarse 

 crystallization. 



Laminated Structure in Steel.§ — Y. A. Fechtchenko-Tchopovsky 

 describes the laminated structures found in rolled steel such as rails and 

 boiler-plates, and discusses their causes and the possibility of removal 

 by heat-treatment. A markedly laminated structure found in a boiler- 

 plate was partially or wholly removed by annealing followed by air- 

 cooling, the effect being greater as the anneahng temperature was 

 higher. The laminated structure reappeared when the steel was again 

 annealed and slowly cooled. 



* Rev. Metallurgie, xii. (1915) pp. 655-6 (2 figs.), 

 t Int. Zeitschr. Metallographie, vii. (1914) pp. 3-34 (30 figs.). 

 X Rev. M6tallurgie, xii. (1915) pp. 155-60 (7 figs.). 



§ Rev. Soc. Russ. :M6tallurgie, ii. (1913) pp. 140-50 (20 figs.), through Rev. 

 Metallurgie, xii. (1915) Extraits, pp. 269-73 (14 figs.). 



