Influence of scandium on the anomalous self-diffusion in b. c. c. -zirconium
For further information on the origin of the anomalous self-diffusion in the b.c.c. phase of IVb metals and alloys the temperature dependence of /sup 95/Zr-diffusion and the isotope effect of /sup 88/Zr and /sup 95/Zr were measured in alloys with 6.7 and 13.6 at. % scandium. The Arrhenius plots are more strongly curved than those for self-diffusion in pure ..beta..-Zr, quite the opposite to previous findings in Zr-Nb alloys. The results of the isotope effect are consistent with a predominant monovacancy mechanism. The diffusion anomaly is explained by phonon assisted diffusion jumps. Induced by the softening of the LA 2/3<111> phonon mode, which results in a continuous decrease of the free enthalpy of migration with decreasing temperature. With this assumption values of the frequency factor and the activation enthalpy representing normal diffusion behaviour are calculated. A systematic variation in the electronic structure when alloying Vb and IIIb metals, respectively, to IVb metals is responsible for the continuous change in the diffusion anomaly of ..beta..-Zr-Nb alloys, pure ..beta..-Zr and ..beta..-Zr-Sc alloys.
- Research Organization:
- Institut fur Metallforschung, Westfalische Wilhelms-Universitat Munster, 4400 Munster
- OSTI ID:
- 5650682
- Journal Information:
- Acta Metall.; (United States), Journal Name: Acta Metall.; (United States) Vol. 35:7; ISSN AMETA
- Country of Publication:
- United States
- Language:
- English
Similar Records
Interdiffusion in the high temperature b.c.c. {beta} Hf-Zr solid-solution
Isotope effect in niobium self-diffusion
Related Subjects
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOYS
ARRHENIUS EQUATION
BCC LATTICES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CUBIC LATTICES
DAYS LIVING RADIOISOTOPES
DIFFUSION
ELECTRON CAPTURE RADIOISOTOPES
ENTHALPY
EQUATIONS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
INTERMEDIATE MASS NUCLEI
ISOTOPE EFFECTS
ISOTOPES
METALLURGICAL EFFECTS
NIOBIUM ALLOYS
NUCLEI
PHONONS
PHYSICAL PROPERTIES
QUASI PARTICLES
RADIOISOTOPES
SCANDIUM ALLOYS
SELENIUM ALLOYS
STRUCTURAL CHEMICAL ANALYSIS
TEMPERATURE EFFECTS
THERMODYNAMIC PROPERTIES
ZIRCONIUM 88
ZIRCONIUM 95
ZIRCONIUM ALLOYS
ZIRCONIUM ISOTOPES