276 HEYCOCK AND NEVILLE: DILUTE SOLUTIONS OF ALUMINIUM IN GOLD. 
Plate 5. 
10. A1 14. 80 diameters. 
Molten and annealed at 535° C. for 4 hours, cooled to 440° C.; annealed for 17 hours, cooled to 
418° C.; annealed 4 hours, cooled to 400° C.; annealed 1'5 hours, chilled. 
Shows the effect of the recalescence on the alpha; a control ingot similarly treated, but chilled 
at the termination of the anneal at 418° C., has no pattern except traces of hair- lin e 
polygonal boundaries. 
11. A1 15. 200 diameters. 
Annealed at 545° C. for 23 hours, chilled. 
Shows the white, uniform, alpha, and the dark, almost uniform, beta. A pre-recalescence 
pattern. 
12. A1 15. 200 diameters. 
Plunged molten into bath at 535° C., annealed for 6 hours, cooled to 520° C.; annealed 2 hours, 
cooled to 380° C.; annealed 12 hours and chilled. 
A post-recalescence pattern, showing new detail in alpha and in beta. 
13. A1 18. 350 diameters. 
Plunged molten into bath at 506° C., annealed 3 hours, cooled to 410° C.; annealed for 18 hours 
and chilled (compare with fig. 3). 
Shows the recalescence detail in both alpha and beta. 
14. A1 23. 320 diameters. 
Melted and plunged into bath at 560° C., cooled in 1 - 5 hours to 420° C. and chilled. Same ingot 
as that of fig. 9b. 
The large dark is D primary. The small pattern is the L eutectoid complex of alpha and D. 
15. A1 23. 320 diameters. 
Similarly treated to the preceding, but cooled to 400° C. before chilling. 
Shows the effect of the recalescence on the eutectoid. 
16. A1 20. 20 diameters. 
Plunged molten into bath at 530° C., annealed 1 hour, cooled to 440° C .; annealed 17 hours and 
chilled. 
The white polygons of D crystallised out of the uniform solid beta when the temperature fell 
to the cL line. 
17. A1 20. 50 diameters. 
Plunged molten into bath at 506° C., annealed 3 hours, cooled to 410° C.; annealed 18 hours and 
chilled. 
This represents the final condition of A1 20 after recalescence and a long anneal; it consists of 
Y with a trace of residual alpha in small particles. 
18. A1 20. 50 diameters. 
A control ingot to the forced recalescences of the alloys described below. The ingot was placed 
molten in bath at 560° C., cooled to 508° C., and chilled. 
It consists of uniform beta; under oblique lighting it resembles fig. 4. 
19. A1 20. 50 diameters. 
Similar treatment to the preceding, but, in addition, the ingot was forced to recalesce at 508° C. 
by touching with a cold wire, the reaction causing the temperature to rise to 523° 0. A 
few minutes later, when the temperature had again fallen to 508° C., the ingot was 
chilled. 
There are large crystal skeletons- of the new body Y bordered by a white substance which is, 
presumably, alpha. 
20. A1 20. 160 diameters. 
The same ingot and treatment as that of fig. 19. An enlarged view. 
21. A1 20. 50 diameters. 
A forced recalescence at 514° C. Temperature rose to 524° C. and remained at that temperature 
for some minutes through the heat evolved in the reaction. There was consequently 
some fusion and the dark matrix is beta reformed on solidification. The crystal skeletons 
are of Y. 
