574 SUMMARY OF CURRENT RESEARCHES RELATING TO 



ternary system, H. C. H. Carpenter* and C. A. Edwards have studied 

 the microscopic characteristics of annealed and quenched specimens of 

 alloys containing up to 60 p.c. zinc and 16 p.c. aluminium. No true 

 ternary compound or eutectic is deposited from the liquid alloys. The 

 inversion of (S into the eutectoid a -f- y is clearly illustrated liy photo- 

 micrographs. The tendency of the a group of alloys to form twin 

 crystals is very pronounced in specimens that have been annealed. 



Cold-working and Annealing of Zinc.| — G. Timofeef has ex- 

 amined microscopically small ingots of zinc as cast and after various 

 processes of cold-working and annealing. Re-crystallization of the 

 severely compressed ingot proceeds very slowly at 20-25° C. ; at 65° C. 

 a change is evident in a few minutes. The speed of re-crystallization, 

 and the size of the resulting crystals, increase rapidly with rising tem- 

 perature. Yery slight deformation is sufficient to cause twinning ; the 

 twinning lamellas are readily removed by annealing at 200° C. The 

 photomicrographs given clearly illustrate the changes studied. The 

 sections were etched with dilute nitric acid to which had been added a 

 small quantity of a 6 p.c. solution of chromic acid. 



Solubility of Carbon in Nickel. f — By heating molten nickel in 

 contact with carljon and quenching the melt, 0. Ruff and W. Martin * 

 have determined the temperature-solubility curve in the range 1550- 

 2500° C, and find that at 2100° C. a maximum of solubility is reached at 

 6*42 p.c. carbon, corresponding to the formula NigC. In no case did 

 the combined carbon exceed 1 p.c. in the quenched specimen, the 

 remainder being graphite. The carbide NigC was identified micro- 

 scopically in the quenched specimens as a brown constituent, very 

 resistant to the numerous etching reagents used, and easily distinguished 

 from the graphite and the nickel present in the sections. The carbide 

 appears to form a eutectic, or eutectoid with nickel. The resemblance 

 of the nickel-carbon system to the iron-carbon system is pointed out. 



Structure of Galvanized Iron.§ — W. Arthur and W. H. Walker 

 have examined transverse sections of samples of galvanized iron manu- 

 factured by different processes. The sections were etched with a " 5 p.c. 

 solution of nitric acid in 95 p.c. alcohol. Four layers were distinguished 

 in hot-galvanized iron : (1) iron ; (2) " binding alloy " — the crystals of 

 unknown composition which first separate from a molten solution of 

 iron in zinc ; (3) the compound FeZug ; (4) zinc permeated by minute 

 crystals of the compound FeZn^. In Sherardized iron, the coating may 

 vary from a thin layer of FeZug with a more or less distinct layer of 

 the " binding alloy," to a thick coating of zinc-iron alloys with a surface 



♦ Int. Zeitschr. Metallographie, ii. (1912) pp. 209-42 (37 figs.), 

 t Comptes Rendus, civ. (1912) pp. 430-2 (8 figs.), 

 i MetaUurgie, ix. (1912) pp. 143-8 (9 figs.). 



§ Journ. Ind. Eng. Ghem., iv. (1912) pp. 397-402, through Journ. Soc. Chem. 

 Ind., xxxi. (1912) p. 644. 



