of Bronzes from Machu Picchu, Peru. 



551 



monly observed in strained metal which has not been annealed 

 sufficiently to cause complete recrystallization throughout the 

 mass, e. g., fig. 48. The entire field is traversed by a set of 

 lines, ab, cd, etc., which cut any vertical line into a number 

 of segments intended to represent the mean number of recrys- 

 tallized grains which would normally be counted along a unit 

 length upon the prepared specimen after anneal at the corre- 

 sponding temperature. A linear relationship is assumed in this 

 construction, but, obviously, any experimentally proven rela- 



T 3 



Fig. 6. 



T 5 



T 7 



T 8 T 9 



"S.S 

 "3 g 

 9 so 



o O 

 13 o 



3i 



w <l> 



3 'a 



■~ a 



S-. ' — 



<t> 



11 



^ jt~^r~~~ 















p^ 













vNaC^OOv \. 











■H 





S$\ 









b 

 d 



T 9 



T 6 



TV 



T,T? T 4 



Temperature. 



(Number and size of grains, resp., fragments.) 



Ts 



tionship between grain size and annealing temperature may be 

 depicted in similar manner. 



By cold- working metal of definite grain characteristics, e. g., 

 uniformly recrystallized metal of the mean grain size which 

 would be produced by complete anneal at T 9 , the grain struc- 

 ture is broken down, inner surfaces develop and new, latent, 

 grains of a lower order of size and stability are formed. As 

 already stated, these secondary particles cannot be distinguished 

 under the microscope. Etching peculiarities, diminishing 

 contrast, lines of deformation, etc., are, indeed, visible when 

 deformation has been severe, but no direct indication of the size 

 or shape of the ultimate secondary units can be obtained. As 

 far as direct observation goes, these new structure elements 

 are latent only. Upon annealing, they assert a modified 

 individuality wherein mutual readjustment and coalescence 

 cause them to become visible units with definite orientation 

 and the dimensions characteristic of the annealing temperature 

 adopted. 



