STRUCTURE AND NATURE OF TROOSTITE 



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Fig. 3 — Mag. 3500X. Fig. 3 sliows the early stages in the formation of troos- 

 titic nodules. The background will be recognized as martensite. The dark particles 

 are troostite. The field is on the border of an area containing large well developed 

 nodules. This position in the specimen is one in which thermal conditions promoted 

 tne development of the needle structure but did not fully inhibit the development of 

 nodules. The very small dark particles are about five-millionths of an inch in diam- 

 eter. The larger ones are from about ten to twenty times larger. 



