Influence of scandium on the anomalous self-diffusion in b. c. c. -zirconium

Journal Article · Wed Jul 01 00:00:00 EDT 1987 · Acta Metall.; (United States)

DOI:https://doi.org/10.1016/0001-6160(87)90129-5· OSTI ID:5650682

Herzig, C; Kohler, U

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), Vol. 35:7
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
NIOBIUM ALLOYS
METALLURGICAL EFFECTS
SCANDIUM ALLOYS
SELENIUM ALLOYS
ZIRCONIUM ALLOYS
ARRHENIUS EQUATION
BCC LATTICES
DIFFUSION
ENTHALPY
ISOTOPE EFFECTS
PHONONS
STRUCTURAL CHEMICAL ANALYSIS
TEMPERATURE EFFECTS
ZIRCONIUM 88
ZIRCONIUM 95
ALLOYS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CUBIC LATTICES
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
EQUATIONS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
INTERMEDIATE MASS NUCLEI
ISOTOPES
NUCLEI
PHYSICAL PROPERTIES
QUASI PARTICLES
RADIOISOTOPES
THERMODYNAMIC PROPERTIES
ZIRCONIUM ISOTOPES
360102* - Metals &amp; Alloys- Structure &amp; Phase Studies