Evidence of a Correlation Between the Transition Temperature for Ordering and the Activation Energy for Ordering Kinetics in Ni75Al25-xFex Superalloys

Abstract

AbstractKinetics of long-range ordering was studied in the alloys Ni75Al25-xFex by means of in situ resistometry. The alloys under consideration exhibit a dramatic decrease of the "order-disorder" transition temperature Ttr with increasing X. After the existing theoretical models, the activation energy of long-range ordering should depend on one hand on the energy of ordering - related to Ttr -, and on the other hand, on the current value of the LRO degree. The performed measurements yield an experimental evidence of the above relationships. In addition, a considerable effect of magnetic order on LRO kinetics has also been registered. The results are qualitatively discussed in terms of the model of LRO kinetics in L12 structure proposed by Schoijet and Girifalco.