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THE REORDERING TRANSITION IN LAYER DISORDERED SOLIDS: RARE EARTH - TRANSITION METAL INTERMETALLIC ALLOYS.

Planar faulting in in rare earth - cobalt alloys with type structures ThNi and ThZn are studied. The structure changes from hexagonal for heavy rare earth to rhombohedral for light rare earth, all exhibiting different degrees of planar disorder. Faulting is quantitatively studied beyond the model of...

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Published in:Revista Cubana de Física Vol. 32; no. 2; pp. 74 - 80
Main Authors: PENTON-MADRIGAL, ARBELIO, ESTEVEZ-RAMS, ERNESTO, AZANZA-RICARDO, CRISTY, LORA SERRANO, RAYMUNDO
Format: Article
Published: Universidad de La Habana 2015
Subjects:
Rare earth metals
Intermetallic compounds
Alloys
Cobalt alloys
Diffraction patterns
Crystals
Online Access:View this record in EBSCOhost
Summary:Planar faulting in in rare earth - cobalt alloys with type structures ThNi and ThZn are studied. The structure changes from hexagonal for heavy rare earth to rhombohedral for light rare earth, all exhibiting different degrees of planar disorder. Faulting is quantitatively studied beyond the model of independent faulting events showing the strength of direct solutions to extract defects information from the diffraction patterns. It is showed that the analysis of the decaying term of the probability correlation function, does not only allow to quantify the loss of memory in the system through the correlation length but also, the strength of interaction between faults. The behavior of the decaying terms turns not to be of universal character when scaled against the correlation length and instead depends on the interaction of faulting. The reconstructive phase transition in this system seems to follow a path where the new phase appears within the disordered phase and grows without homogeneous reordering of the disordered arrangement.
Se estudia la ocurrencia de defectos planares en aleaciones de tierras raras - cobalto con estructuras tipos Th2Ni17y Th2Zn17. La estructura cambia desde hexagonal para tierras raras pesadas hasta romboédrica para tierras raras ligeras. La ocurrencia de defectos se estudia cuantitativamente m3s all3 del modelo de ocurrencia de defectos independientes mostrando la robustez de las soluciones directas para extraer información sobre defectos a partir de los patrones de difraccion. Se demuestra que el análisis del termino de decaimiento de la funcion de correlacion de probabilidades, no solo permite cuantificar la perdida de memoria en el sistema a travos de la longitud de correlación, sino tambien el grado de interaccion entre defectos. El comportamiento del termino de decaimiento muestra no ser de carácter universal cuando este es escalado respecto a la longitud de correlación y en su lugar depende de la interacción entre defectos. La transicion de fase reconstructiva en este sistema parece seguir un recorrido donde la nueva fase emerge dentro de la fase desordenada y crece sin un reordenamiento homogéneo del arreglo desordenado.