Dilatometric technique for evaluation of the kinetics of solid-state transformation of maraging steel

1993 ◽  
Vol 24 (12) ◽  
pp. 2653-2656 ◽  
Author(s):  
U. K. Viswanathan ◽  
T. R. G. Kutty ◽  
C. Ganguly
Keyword(s):  
Solid State ◽  
Maraging Steel ◽  
State Transformation ◽  
Solid State Transformation ◽  
Kinetics Of

Nucleation kinetics of ellipsoidal shaped nucleus on a dislocation during a solid state transformation

1988 ◽  
Vol 22 (8) ◽  
pp. 1189-1193
Author(s):  
P. Sureshkumar ◽  
C. Subramanian ◽  
P. Ramasamy ◽  
M.N. Shetty
Keyword(s):  
Solid State ◽  
Nucleation Kinetics ◽  
State Transformation ◽  
Solid State Transformation ◽  
Kinetics Of

The kinetics of the solid state transformation of racemic to optically active 1,1′-binaphthyl

1977 ◽  
Vol 55 (5) ◽  
pp. 889-894 ◽  
Author(s):  
Keith R. Wilson ◽  
Richard E. Pincock
Keyword(s):  
Solid State ◽  
Active Phase ◽  
Reaction Rates ◽  
Optically Active ◽  
State Transformation ◽  
Arrhenius Activation Energy ◽  
Solid State Transformation ◽  
Crystal Forms ◽  
Spontaneous Nucleation ◽  
Kinetics Of

Rates of the solid state reaction which thermally converts racemic to optically active 1,1′-binaphthyl (mp 158 °C) have been determined at temperatures between 105 and 135 °C using polycrystalline samples. The presence of a sufficiently uniform distribution of enantiomorphic seed crystals results in a smooth conversion of the racemate to the eutectic crystal forms of binaphthyl. Although it is possible to force the resolution reaction almost to completion at higher temperatures (150 °C) where the melt phase is an intermediate, lower final specific rotations are obtained when only solid phases are involved (below 145 °C) because of the independent nucleation of racemic material from the reacting crystals. Both spontaneous nucleation and reaction rates in the solid state were increased by grinding the initially prepared samples and were decreased by the storage of samples. The Arrhenius activation energy of this phase transformation giving optically active product is ca. 60 kcal/mol in a variety of different samples. This is consistent with a mechanism in which a molecule of 1,1′-binaphthyl attains considerable freedom from the racemic solid in order to interconvert to its enantiomer and add to the growing optically active phase.

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